I don't own my game?

@riennnnnnn  No, these errors shouldn't be related.  But it's always possible the same underlying change caused both.  Please make sure the custom content is in the folder Sims 4 is actually reading.  Find the full file path in-game:

https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/

Then compare that to the file path for a cc item.  You can right-click that file and select Properties > General, then look at the Location.

If the skins in fact in the correct folder, please remove them and download and install a fresh copy of one of them, then see whether it shows up in-game.

The other day I got a weird popup about not owning my game. I repaired, took out my entire sims4 folder (inc the Sims4 entire folder so the newly repaired game would have to recreate it all), This resolved the error.

However, my skin cc isn't showing up in game. Any skin overlays are showing up in SkinDetails, but all my actual skins are gone from CAS. I re-downloaded all of them just to be sure everything was fresh (and stuck them in after that initial clean start). Every other piece of CC works. Overlays, makeup, clothing, cc personalities

No matter which one I put in (or how many I put in they're all gone. I have 0 mods running, just a skin cc. I used to have a whole bunch of skins with wreches in them and it was all my skins. I have no idea how to fix this.

I've done a complete reinstall and nothing is working. This is what my CAS looks like, I tried it with multiple skins and with one skin at a time.

Still nothing.