iCloud Drive Thumbnails

Can anyone offer any advice about why Thumbnails don't appear for all photo's when using iCloud Drive on either the IOS App or via the website.

I have a lot of photo's on my iCloud Drive and need to show them to customers at various points of the day but not being able to see the thumbnail preview is really annoying when looking for particular pictures.

Some of the Thumbnails appear but must don't. All of the photo's are JPG format but there doesn't seem to be a pattern between the ones which display and the ones that don't.

I've done some googling and can see see many other users are complaining about this but there doesn't appear to be any fix or even a workaround.

Is this a bug?? Do Apple plan to resolve the issue? This is proving to be so annoying that if there's no way to resolve it I may cancel the subscription for my additional iCloud storage and move to another cloud storage provider. That would be a real shame given that I use an Apple device and would prefer to use Apple for my cloud storage.