MacOS "Made for iPad" builds are not being updated by Xcode

I suddenly noticed that changes I made in code had no effect on the app when I rebuilt it and ran it on my M1 Mac as a "made for iPad" target. The debugger will even stop on new lines and seem to execute them, but they do nothing. If I clean the build folder and re-run, the same line executes as expected.

This wastes an incredible amount of time until you discover what's happening. Now I have to remember to clean build folder every time I build and run.

The application's structure is very simple, with no included libraries or third-party dependencies.

Anybody else seeing this?

Xcode 15.3 under Sonoma (14.4.1).