MPS 3.0 RC4 is ready for download
RC4 contains some major bug fixes, including critical fix to the new mechanism of handling SModel attribute meta-info, introduced in MPS 3.0.
If you already migrated to MPS 3.0 in your projects, you’ll have to apply additional migrations to these projects with “Tools->Scripts->Migration->MPS 3.0->Migrate already migrated to behavior methods attributes.”
Develop with pleasure!
-JetBrains MPS Team