MP1 Debug Configuration: Problem Occurred...
UPDATE: we found that issue comes from the CubeMX (5.40) generated project...
Comparing with a MP1 sample project (ironically from within the Cube repo), the .project file is slightly different. In our project, an extra line is present:
fr.ac6.mcu.ide.core.MCUMultiCoreProjectNature
If we remove this line from the CubeMx .project file, then the issue disappears.


