Why I suddenly don't see a half of psd files tumbnails any more?

[kirk]

I am trying to re-scan  folders sevral times and still see only "Ps"  icons instead of actual thumbnail.  Double click opens file previews just ok at the same time.   What might be a reason for such behavior?   Those  files seems are totally random , not a huge size ones.

ps. looks like they are mostly old psd files up to 2015. Once I re save the file in current Photoshop it turns ok in iMatch.   But I never had such a problem before. 

[Mario]

Why are you trying to rescan folders?
Do add new and updates files to your database?

I assume the files which fail are new to the database so IMatch has to create the thumbnail from scratch.
Did you check the log file for any error messages or warnings?

What happens when you select some of the files with this issue and press Shift+Cltr+F5 and choose "force Update?
Does this create the thumbnail?

Potential reasons for this problem may be another application locking the file or a crash in the image library caused by something in the file (both reasons would show in the log file).

[kirk]

Thanks Mario,  Shift+Cltr+F5  and "force update"  fixes it