Stuck on loading screen December 2020

@Shanna1381  When you moved the Sims 4 folder and started a new save, did that new save load properly?  If not, please try again, this time while your computer is completely offline.  You can sign into Origin and put it in offline mode, then disable wifi and/or disconnect the ethernet cable before launching the game.

If the new save does work fine, copy your existing save to the new Sims 4 folder and see how it runs.  Don't add any other content though, at least not yet.  Since you're copying the save rather than moving it, you don't have to worry about missing custom content—the original save will be intact in the old Sims 4 folder, and you can freely experiment on the new one.

Yes when I moved the old folder and started a new save everything worked fine. But when I copied my saves and mods back in, the problem happened again. I've even tried clearing the cache and tray folders.

@Shanna1381  Test your old saves without your mods.  You can copy them to the new Sims 4 folder rather than dragging and dropping; that way, the originals will be intact and you can freely experiment on the copies.

If the saves work with no mods, you can start adding back your mods in batches, testing each time to see whether the problem reappears.  If and when it does, you'll need to split the last batch you added and retest until you find the problem file(s).