Advanced tab disappears/reappears in Studio 2015

Another weird thing going on with my new installation of Studio 2015..

When I go to a translation segment that doesn't have anything in it on the translation side yet, half of the "Advanced" tab won't show up:

If I then select a different segment that has something in it on the translation side, the rest of the "Advanced" tab magically appears:

The main problem I have with this is that my "Insert symbol" plugin isn't there when I go to a new segment and start working on it.  I have to select out of it, and then come back for it to appear.

Could this be related to that plugin?  The Bookmark stuff also disappears/reappears, though, so maybe it's a program bug?