stairs sometimes cause sims to t-pose and cancel all queued actions

edit: not sure if the attachment was working so here's a youtube link of the video instead: https://youtu.be/rE5d25kdrPg

sometimes when my sims begin walking up/down a set of stairs or up/down a one-step platform, instead of walking all the way up or down and continuing to do what they were supposed to do like normal, they teleport to the top or bottom in the direction they were going, t-pose, and cancel all the actions they had queued. this is something especially frustrating since the place i most often use stairs is the front porch, so when my sims are on their way to work/school sometimes this will happen and the queued action of "go to class/school/work" is canceled and the sim stays home instead of going, which is increasingly more difficult to catch the more sims you have to tend to in your household. i've attached a video of the issue as well.

this is something i've been experiencing for months now, since either the cottage living patch or the one before it, and at first i posted about it in the bug reports forum but at the time it was thought to be caused by one of the mods i had installed and the post got marked resolved and moved to pc tech issues. i haven't played much of the sims since then until recently, when i still noticed this happening. i removed all my mods, repaired the game, and created an entirely new save with the plan of adding mods one at a time to see if one of them caused it but before i added any it happend again, so i know for sure now it is my game and not my mods. there was even an issue not long ago where i had to factory-reset my pc and i had to re-isntall the sims completely. the only constant through all of this is the sim i've been using. is there anything else i could do to determine what the cause of this is? is it possible the bug latched onto the sim i made before a similar issue was patched and caused it to stick around? i've already done every reccommended step to address the issue and at this point its kinda just ruining the game for me.

edit 2: also here's the two videos i have from a few months ago when i first made the bug reports post, i forgot i had them. the first one you see it in the lower left-hand corner. (video 1): https://youtu.be/ZZPUXTrE5Rk (video 2): https://youtu.be/VVqUjxRVz_s