On the 'testingCheatsenabled true' cheat, did you choose 'Trigger age transition' or 'Edit in CAS' (for the CAS, you choose the next life stage)? If you did one, do the other. If you tried both, have you done the 'resetSim' cheat on them? And have you removed any 3rd custom content/mods you may have, as well? I hope this helps!
Welcome to the forum by the way