If I use an inferred mapping model the duplication issue does not occur. If I create a new mapping model with no changes to the generated Xcode file, the issue still occurs.

Experiencing this for the first time in Xcode 15.3. Is there a workaround? Why is this happening?

I am experiencing this as well in Xcode Version 15.3 (15E204a). If I create a new project they build previews and tests just fine. I have tried to figure out the different in build settings or scheme to see if there is anything I need to update, but I couldn't find it.

I've also noticed the Other error starting in September,

How long does it take to get a response to the entitlement request? I asked 2 weeks ago but haven't seen an update yet.

I am having the same issue with Xcode 16.2 on Sonoma. I'm using SF Symbols 6. Exporting my symbol I selected Xcode 16 compatibility, and it said my symbol can be used with SF Symbols 4.0 and above. Then I add into Xcode and I can build for iOS, but not macOS through Catalyst due to the same issue.