Hello!
Yeah, that shouldn't be happening... Hm a few things that come to mind from this scenario are...
1. Re-enabling the canvas might not be properly telling child STM objects to re-appear/re-make their meshes. Is this behaviour any different when the GameObject the canvas is on is turned on/off instead? Not sure if I already is, but need to check since this can narrow it down! (If this is the case, will look into why STM isn't updating in this scenario, but that's a quick working fix for you) I have a few ideas on how to fix this if it's the problem.
2. Inside of an animation, please enable the "forceAnimation" variable on the text, at least for the frames where it will appear/disappear. This was intended as an optimization feature for animating text, but if a parent object is being set active/inactive, I can see the text or certain animations refusing to play. You can also try disabling "autoRead" or enabling "rememberReadPosition"... Those variables are true by default so if I had to guess, it's probably trying to read but refusing to automatically animate during the animation triggering it.
So, please give those a shot! setting the canvas's gameobject active/inactive, and enabling "force animation" on STM.