AutoFades setup causing problem

Only in busy project, not in a new one. When I want to change autofades, “A serious problem has occured”. No matter which version the project has been created in. Every new project can be setup flawlessly, but when I work for a while, add some instrments, record some tracks and then want to change it, the message appears.
Everything up to date.
Cubase 64bit 2019.5.9 (1.58 MB)


This is an known issue, already reported to Steinberg.