I found this and it worked for me. Was this what you meant? https://stackoverflow.com/a/61323987

Exactly the same issue, looks like I too am gonna have to go elsewhere like mapbox or something

I did, but unless I'm missing something I can't see where what he is saying and how he resolved it fits into my issue. Since, after more testing, the issue is still present if I cut out the @FetchRequest and just use static mock data instead, directly to the annotationItems parameter. I also found, for me at least, running the Apple example of MapAnnotation (https://developer.apple.com/documentation/mapkit/mapannotation) also gives me tons of Runtime Warnings. Should this be the case?