Same. I have the same specs as you. It's driving me crazy.

I can compile and run the project but I cannot use previews with Xcode 26.0.1. My projects needs to have "use legacy previews execution" switch enabled otherwise all previews are crashing during initialisation for same strange reason I have given up looking for a solution. With Xcode 26.0.1 the "automatic" build executed for legacy previews always fails with this error message so now I'm not able to use previews at all.