I am sorry that you are having this issue. When it occurs, try resetting the yoga teacher and see if that helps to unfreeze the other sims.
If you have cc/mods in your game, move your mods folder to the desktop. Then start the game and see if the issues are still there.
Sometimes having a large amount of items in the sims inventories and household inventory can cause issues. Try removing some of the items from the inventories and see if that helps.
Try lowering your graphics settings.
I Tried to reset him 100 times, I tried to see if the yoga teacher's mat properly placed and there is nothing on the way. I tried going to the different Spa with the different yoga teacher, seams like there is no problem. Only in this particular Spa the teacher is glitching.