Solved
Marketplace stuck in loading screen
I load into Sims 4 and click to search the marketplace. Marketplace shows up, but when I click on a kit or a pack or a creator-made thing, it does just like the screenshot and never loads.
Those of you still running into this, do update your mods. That includes UI Cheats Exception (which is likely to rebreak today, though), which is the only one I can think of off the top of my head that was blocking the Marketplace.
