I am having the same issue.
It has been suggested that it is caused when you task a sim and then move away from them so they are no longer in view. I did not go back in yet to test to see if that is the only time it happens, but it definitely DID happen multiple times when I did that; just unsure if it also happens other times. But yes, when out of view they no longer complete items in their task queue and when you go back to them, you have to cancel at least the next task to get them to move again.
I have no mods or cc installed and have packs except the Batuu one and two of the kits.
It is making it pretty difficult to play a family.
