Hey! I'm about to go to sleep, so here's my immediate thoughts before I dig deeper into this...
For the "auto pause" functions, STM is picky about the height of a text box being a multiple of the text size. (If the text is 2 units tall, the box height should be exactly 8 if you want 4 lines, for example) Could it be that? That's an old, unfortunate behaviour I never got around to changing... but hopefully an easy enough one to work around. So I'm just wondering if it's this... even though you said it's only effecting auto pause full. Please let me know what happens and I'll take a closer look soon!