Notification wall / inventory / options menu

xtinkerrx​  Does this happen if you remove everything in the inventory?  I realize you might not want to sell or delete all these items, but it's a useful test, and you don't need to save your progress.  Or you can use "save as" to rename the save, and not overwrite the original, if you need to quit and reload.

If this helps, you can go back to your original save and delete items until you find the culprit, then revert to the original save again and remove only what's necessary.

If this doesn't help, please test a new save, for comparison's sake.  You can create a new sim and have them buy some items wherever you like, then save/quit/reload to see whether you can reproduce the error.