[GALLERY] 'Content not installed' warning with all content owned

I am having a similar problem, except I don't have any CC or Mods. I've been trying to build a new save moving my older lots and sims into a brand new save -- and it was working perfectly up through the March 17 update. Then the March 18 one started causing issues on my Macbook laptop. When I try to download content I saved on March 17 it says I own everything when I open it in my library, but when I try to download Sims it says "Content Not Installed".

It's worse with lots. They won't load at all. They just get stuck in a loop after that "Content Not Installed" message and I see a little red "System Error" message flash as it tries and fails to load a lot. I am beginning to suspect that it has to do with the Sims 4 Bonus Content which now says that it's available on PCs only?

I have done everything to try to fix this, including a full uninstall, reinstall, but I'm still having issues. I asked AI and a solution it came up with was just going into an old save and resaving the lots after the March 18 update. So I tried that and the game crashed. This March 18 update may have fixed things for console users, but it has definitely messed things up for Macbook users.