It seems some Cubase session open from file explorer and some do not.
These may be sessions that were not created with 8.5 but I am not quite sure yet. I believe this is happening even with 8.5 sessions.
- Open Cubase
- Find a previously opened project in File Explorer and double click.
- Cubase comes to the top but the session does not open.
Work around is to use the “Open” function under the file menu.