My sim will not age or gain celebrity points. Every time they get a promotion, they're instantly demoted. Her wife, however, is aging, gaining celebrity points, and advancing in her career. I tried resetting her, but it didn't work. Any ideas on how to fix this? I don't save very often, so I'd like to do whatever I can to avoid going to a backup.

Also I feel like I should add that this save file is 4 generations old (5 if you count the founders as generation 1, rather than the first heirs), so it could just be a glitch due to an enormous save file.

Hmm, I've come across this behavior too. Some of my Sims would get to level 8 or 9 of a career and get a promotion at the end of the day, only to receive a message saying that their performance sucks (it didn't) and they were demoted to the previous level.

This is a shot in the dark, but do you have Story Progression installed? Some careers (I think Political and Criminal/Evil) restrict the last level to only one Sim, and that position may already be filled.

Also, I think I've seen this behavior once where my Sim did have a great performance metric but their skills were awful for the position they were being promoted to. As soon as I fulfilled the requirements (good skill level, good relationship with boss/coworkers etc.), my Sim was able to get a promotion and stay in that position.

About the no aging aspect: is the Sim an occult, specifically a vampire? I think SP has a setting under Castes \ Vampires called "Allow Aging", and if that setting is set to False, then no vampire in town will age.

I do have story progression, but my sim is only being promoted to level 3 of the film career from late night, and she's not a vampire. I'm going to install error trap and overwatch to see if they can catch anything wrong with her

Just a suggestion: You might want to consider keeping both mods in your game. Error Trap and Overwatch provide a lot of game clean up. Error Trap does save game clean up and reports any game errors and Overwatch makes corrections of persistent or recurring errors produced by the Core game or other mods, resets sims and objects as well as performing nightly clean up when playing. In addition see Overwatches What Does This Mod Do Automatically?