Thank you Richard for reaching out.
Some answers to your additional questions.
I use iCloud Photos to synchronize my devices,
Optimize Storage is activated,
I use iCLoud drive (200 Gb),
368,03 GB of 499,9 GB available.
I never noticed these problems. Perhaps even my storage on the external drive is (without my knowledge) corrupted.
The only thing I can think of is that the update to Sequoia 15.6 is the problem.
Extra information:
Some of the photos are original jpg’s, sometimes NEF’s from Nikon, sometimes PNG etc. Some are edited, som are not.
After doing some research I discovered that NEF’s which has been edited and stored as jpeg give some problems when exporting them.
When exporting however as originals they give no problems, but then the editing is lost.
When trying to edit such a photo, Photo’s can’t edit them anymore, not even in raw mode.
You can export them as jpeg, HEIC, PNG or TIFF. HEIC however can give problems too when exporting as HEIC. (IMG_0581.HEIC uit 2018) (unknown failure)
mov’s are exported in heir without a problem.
Conclusion for the moment: only export them in Photo’s, using the original photo.
(Perhaps the problem is solved in Tahoe, I hope)
Again, thanks a lot for your help, I really appreciate it.
Kind regards,
JosV