Single Sim's Outfits Won't Save (Others' Will)

Do you have any mods or custom content (CC) in your game? Could you test without?
You can just move the folder to a location outside the Electronic Arts folder.
If the game works without your CC and mods in, your issue is probably caused by a broken mod or CC.
You can find a full list of broken/incompatible CC and mods since the Cats and Dogs expansion pack launch over here:
http://forums.thesims.com/en_US/discussion/928106/broken-mods-cats-and-dogs-nov-2017

I have neither. I do cheat a lot, though--using ctrl+shift+c, "testingcheats on," "cas.fulleditmode," and "Modify Needs, Make Happy" almost as soon as I'm on.

...unless I've downloaded CC unbeknownst to me through the Gallery by getting a premade house or something.

Thank you for your response!

Would you be able to upload the Sim to the gallery and give me the username or link to the Sim?

Yea, sure. How do you upload a character who's already completed, though? I only see where I made her months ago--it's an extremely old version.

You can do this when you're in CAS (Create-A-Sim) through the mirror or closet. Click the little folder in the corner:

Then upload it to the gallery through there:

Thank you! I've been wondering that for a while lol.

Household name is "Oxenfree." It has "#SPHYNX"--automatically added. My username, of course, is "Cold_Pastoral" (at least, I hope that's it). When I searched for "Oxenfree" in the Community tab, it came up as first: Ollie Oxenfree. 

Well, the good news is, I have the same issue with her, so it's not your computer. The bad news, there is an issue. I've forwarded it to our bug investigator, I'll probably hear back soon! 

OK, geez. Thank you so much for the help! I will be waiting patiently :o)

Hey @Cold_Pastoral, while looking into this issue our tester found that you can fix your Sim by selecting them, selecting Change to Nude, and then selecting the wardrobe. Let me know if that works for you! It might cause issues with your gallery upload snapshot, in which case you can also try downloading "Oxenfree Fixed" from account-name RiseOfThePandas, which was created by our tester who was troubleshooting this. 🙂