I uninstalled older versions (7 thru 9.5) . File association now seems to work OK.
FYI when the problem existed all .cpr files in Windows explorer displayed with the default blank icon. Once I removed older Cubase versions the .cpr files displayed with the correct Cubase icon and launched Cubase 11.
Yes, the blank icon was what I was seeing in File Explorer, as well. I could set the association to be Cubase 10 or 10.5, and it got the right icon and called up the right program. When I set it to 11, though, it got the blank icon and called up 9.5. I may just go ahead and uninstall 9.5 since I really can’t imagine using that at this point, or even 10, for that matter. Only reason I’d go back to 10.5 would be if something in 11 broke badly or I just wanted to check behavior in an earlier version. (That is, assuming, of course, that I can open older projects in 11 – I only started with Cubase at 9.5.)
Thanks, amoon56. I just uninstalled Cubase Pro 9.5 and confirmed that doing that both brings back the File Explorer icon and lets double-clicking on a .CPR file bring up Cubase 11. The issue definitely started for me after the 11.0.10 update.