Hm.... you are right that it also breaks when using shift-right click.

At the same time restarting 7tt also fixes the problem, so it does seem to have something to do with 7tt (unless there's a flaw in my logic I'm not aware of). Or something 7tt does on initializing fixes the problem? ¯\_(ツ)_/¯

EDIT: Oh, I should mention that I am using StartIsBack, which has been known in the past to have interactions with 7tt.

It is resolved.

Honestly I did not expect a response, so I am both pleasantly surprised and thankful.