We just saw that there is conflict with the scheduling feature from gmail (currently rolling out) that prevent the composeview handlers to work correctly.
The error is that the send button (that seems to be an anchor on your side) is not found at the compose opening even if the dom element is present.
Did you already see this issue ? It seems that you have a logging system, so you are maybe already aware of that.
Uncaught Error: Failed to find element with selector: .IZ .Up > div > [role=button]:not([class*=inboxsdk])
at r (platform-implementation.js:99)
at t.value (platform-implementation.js:81)
at t.value (platform-implementation.js:81)
at eval (platform-implementation.js:81)
at Object._handleValue (platform-implementation.js:42)
at Object._handleAny (platform-implementation.js:42)
at _$handleAny (platform-implementation.js:42)
at m (platform-implementation.js:42)
at Object._on (platform-implementation.js:42)
at Object.onAny (platform-implementation.js:42)
at Object._onActivation (platform-implementation.js:42)
at Object._setActive (platform-implementation.js:42)
at Object._on (platform-implementation.js:42)
at Object.onAny (platform-implementation.js:42)
at Object._onActivation (platform-implementation.js:42)
at Object._setActive (platform-implementation.js:42)
at Object._on (platform-implementation.js:42)
at Object.onError (platform-implementation.js:42)
...
<table id=":ry" class="IZ" role="group">
<colgroup>
<col id=":rz">
<col class="Uf">
<col class="UA">
<col class="Uy">
<col class="az8">
<col id=":q3">
</colgroup>
<tbody>
<tr class="btC">
<td class="gU Up">
<div id=":pu" class="J-J5-Ji btA">
<div id=":qy" class="J-J5-Ji"></div>
<div class="dC">
<div id=":s0" class="T-I J-J5-Ji aoO v7 T-I-atl L3" role="button" tabindex="1" data-tooltip="Send ‪(Ctrl-Enter)‬" aria-label="Send ‪(Ctrl-Enter)‬" data-tooltip-delay="800" style="user-select: none;">Send</div>
<div id=":rw" class="T-I J-J5-Ji hG T-I-atl L3" role="button" tabindex="1" aria-label="More send options" data-tooltip="More send options" data-tooltip-delay="800" aria-expanded="false" aria-haspopup="true" style="user-select: none;">
<div class="G-asx"></div>
</div>
</div>
<div id=":qz" class="J-J5-Ji"></div>
</div>
</td>
<td id=":qk" class="oc gU">
<div data-tooltip="Formatting options" aria-label="Formatting options">
<div id=":tr" class="J-Z-I J-J5-Ji" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H">
<div class="J-J5-Ji J-Z-I-J6-H">
<div class="dv">
<div class="a3I"> </div>
</div>
</div>
</div>
</div>
</div>
</td>
<td class="gU btB">
<div class="Uz" aria-hidden="true"></div>
</td>
<td id=":qe" class="a8X gU">
<div class="bAK" style="user-select: none; position: relative;">
<div class="wG J-Z-I" command="Files" data-tooltip="Attach files" aria-label="Attach files" tabindex="1" id=":tt" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div id=":ts" class="a1 aaA aMZ" style="user-select: none;">
<div class="a3I" style="user-select: none;"> </div>
</div>
</div>
</div>
</div>
<input type="file" name="Filedata" multiple="" style="position: absolute; overflow: hidden; height: 0px; width: 0px; opacity: 0; left: 0px; top: 0px; display: none;">
<div class="wG J-Z-I" command="+link" data-tooltip="Insert link ‪(Ctrl-K)‬" aria-label="Insert link ‪(Ctrl-K)‬" tabindex="1" id=":tv" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div id=":tu" class="e5 aaA aMZ" style="user-select: none;">
<div class="a3I" style="user-select: none;"> </div>
</div>
</div>
</div>
</div>
<div class="wG J-Z-I" command="+emoticon" data-tooltip="Insert emoji ‪(Ctrl-Shift-2)‬" aria-label="Insert emoji ‪(Ctrl-Shift-2)‬" tabindex="1" id=":tx" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div id=":tw" class="QT aaA aMZ" style="user-select: none;">
<div class="a3I" style="user-select: none;"> </div>
</div>
</div>
</div>
</div>
<div class="wG J-Z-I" command="docs" data-tooltip="Insert files using Drive" aria-label="Insert files using Drive" tabindex="1" id=":tz" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" aria-disabled="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div id=":ty" class="aA7 aaA aMZ" style="user-select: none;">
<div class="a3I" style="user-select: none;"> </div>
</div>
</div>
</div>
</div>
<div class="wG J-Z-I" command="image" data-tooltip="Insert photo" aria-label="Insert photo" tabindex="1" id=":u1" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" aria-disabled="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div id=":u0" class="a2X aaA aMZ" style="user-select: none;">
<div class="a3I" style="user-select: none;"> </div>
</div>
</div>
</div>
</div>
<div class="wG J-Z-I" command="locker" data-tooltip="Turn confidential mode on / off" aria-label="Turn confidential mode on / off" tabindex="1" id=":u3" role="button" aria-pressed="false" aria-haspopup="true" aria-expanded="false" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div id=":u2" class="buc aaA aMZ" style="user-select: none;">
<div class="a3I" style="user-select: none;"> </div>
</div>
</div>
</div>
</div>
</div>
</td>
<td class="gU az5">
<div id=":r8" class="J-J5-Ji btx">
<div id=":qw" class="J-J5-Ji bty">
<div id=":ud" class="J-JN-M-I J-J5-Ji Xv L3 T-I-ax7 T-I" role="button" tabindex="1" aria-haspopup="true" aria-expanded="false" data-tooltip="More options" aria-label="More options" style="user-select: none;">
<div class="J-J5-Ji J-JN-M-I-Jm"><img class="Y1" src="images/cleardot.gif" alt="">
<div class="a3I"> </div>
</div>
<div class="J-J5-Ji J-JN-M-I-JG"></div>
</div>
</div>
<div class="Uz aw4 J-J5-Ji" aria-hidden="true"></div>
<div class="J-J5-Ji bty">
<div id=":q1" class="oh J-Z-I J-J5-Ji T-I-ax7" tabindex="1" role="button" data-tooltip="Discard draft ‪(Ctrl-Shift-D)‬" aria-label="Discard draft ‪(Ctrl-Shift-D)‬" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-Kv-H" style="user-select: none;">
<div class="J-J5-Ji J-Z-I-J6-H" style="user-select: none;">
<div class="og T-I-J3" style="user-select: none;"></div>
</div>
</div>
</div>
</div>
<div tabindex="1" style="background-color: transparent; width: 1px; height: 1px; position: absolute;"></div>
</div>
</td>
</tr>
</tbody>
</table>