commands disappearing, then not queueing

Hi - I'm not sure if I'm the only one having this issue or not, but here we go...I recently installed the June update and purchased the Island expansion.  My game was getting a bit buggy before but the update fixed most of those issues.  However, now my sims will not follow commands after a bit of gameplay.  They are fine when I first start the game but after 30 or so minutes, regardless of whether I send them to any other lots, the commands will begin to disappear after queueing, then will not queue altogether.  I have no custom content or mods.  Any suggestions are appreciated.  Thanks!