Server Error uploading to gallery/library

Issue (PC)
Whenever I try to save a lot to the library in The Sims 4, I get:

“Server error. We could not process this gallery request. Please try again later.”

This occurs even on empty lots and new saves, across all worlds and saves. Household saving works normally.

Given everything I have tried (and I have been trying for weeks):

• The issue is not caused by mods, CC, objects, packs, EA accounts, or Windows profile.
• Once the error occurs, lot saving fails universally, even in new saves or on new accounts.
• Fresh installs and multiple Windows/EA accounts do not prevent recurrence, ruling out hardware or local system issues.
• The problem is isolated to the Sims 4 lot-save engine / Tray serialization.

Please investigate and provide a fix or workaround to restore full lot-saving functionality. Note that this is reproducible on clean installs and new EA accounts, and is not a user error.

The game is playable, but the inability to save lots is extremely frustrating and limiting. I can't believe how many different things I've tried to get this to work, only to get the error message every time.