Hi there @PurpleSexyCat. I'm also playing on Xbox Series X. Have you seen any error codes with this problem and also did you get the Terms and Conditions pop up again at the start of the game?
I had all my saves affected by taking and storing photos on my previous Xbox so that's useful to know you were taking photos, I lost everything. If you've lost everything already, I don't usually suggest this to players but I'd start again from scratch and this time avoid taking photos to see if it improves. I had to do a console reset and speak to Xbox Support. Occasionally you'll get a Sims player on live chat/callback at Xbox Support if you're lucky and they knew of the issue. I also got advice here. It's a real shame as I was playing the Photography skill and using the Moschino pack.
I've been able to take a few photos with the HSY booth but been careful to place them on a wall straight away and not store them.
If you've got other games you want to keep:
Go to Profile & system>Settings>System> Console info>Select Reset console.
Choose Reset and keep my games & apps. That's if you decide to do that.
Then I had to individually clear Sims 4 from Manage Game and Add-ons. I then restarted from scratch. But I never usually suggest that to anyone unless they've already lost everything.
I've also had issues losing my saves after placing items from the Gallery and Library and using saved rooms. I occasionally place my own rooms from my Library but that's it. Again, Xbox Support knew of that issue and advised against it. I replaced all my lots from my Library and gave myself another problem.
I avoid all of these things now and it's a frustration that I have to do that but so far it's helped and it's been a couple of years or more.
I'm also attaching the console troubleshooting steps for you:
