Changing error messages - differences in reported errors between VS and pyright cli

Describe the bug
After starting n (1<= n <= 10) debug sessions, the reported errors change. Usually at this point in time, the Output-Pylance entry in the drop-down menu disappears

Steps to Reproduce
Open project - Errors reported:

Start debug sessions. After a couple of runs, error reporting will change:

(this has nothing to do with the current problems with flask, another project not using flask exhibits the same behavior)
The change in error reporting always happens, surprisingly this time the output-pylance entry did not disappear:

Notable difference is the line saying "no source files found"

Editing code yields new error messages but only on the new baseline. The initially reported errors are still there but do not get reported.

Expected behavior
Stable and reliable reporting of errors

Additional context and screenshots
I have not been able to force output-pylance to disappear, after some debug sessions it is gone.

Configuration information (If you are providing a diagnostics file (see below), skip this section)
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