I opened a ticket with Google for this, but I also wanted to post it here, just in case someone else has figured out a solution. When I get an update from Google, I will update this post. Hopefully they come back with a solution. Thank you all for your time.
I am using GAM to script changing group settings from *users at domain* can post to *anyone* can post. I have requested, and received the Group Settings API and set up GAM to work properly to modify settings for this.
The issue I am running into is that a few of the groups (more than a few, about 300) are consistantly failing. I run the script, and it throws back *bad request*.
I have done some troubleshooting, and it seems that if I go to Control Panel, and view the group in Groups, then click 'Access Settings' it brings me to the screen in Groups for Business. After I do this for a group, it succeeds with the script I am running. It appears that a change is made to the group when this is done.
Is there any way I can do this 'Access Settings' update via script? Clicking through over 300 groups is not going to work for this.