Hey, thanks for the report and sorry for the slow reply.
All Google accounts don't seem to be created equal, so there are
corner cases where some Google services aren't as accessible with
search depersonalization on. That's why I made the feature optional. I
also have bugs filed against a few of these issues, but resolving them
has turned out to be nontrivial.
I think Google redid how Docs handles logins this week, which is
messing with Disconnect. I'm hoping the workaround I talked about in
the mail I just sent takes care of this problem, too.