Visual studio 2019 does not detect biml file change / cannot save files

Whenever I change an existing biml file the change is not detected (* next to file name in tab), saving the changes does not work.

I tried reinstalling biml (deleted registry and ran as admin) but no luck there.

Visual studio Version 16.7.3

Microsoft SQL Server Integration Services Designer Version 15.0.2000.128 ==> 3.9

Any Ideas are welcome