For some years I had around 200GB of photos on an external hard drive and the photos app also didn't had any problems finding all of the photos.
But after some time I wanted to copy my photos to a NAS system because of the redudancy. I just copied the same folder structure over to the NAS and put the NAS location as a source location in the photos app. But the photos app only shows a fraction of my photos most of them are missing even tho there are clearly on the NAS. I can also browse manuelly to them and open them with the photos app. I also waited for a few days but the photos app never found more photos.
Nothing of that helped. If I browse in the photos app to a location with pictures I only get the message "No readable photos, videos or folders found"
Is there maybe a specific setting I need to take in the NAS system? For now it's normally mapped and can be accessed. I found an article that claims that the subfolders should only contain up to 200 images, is this true? And if so why does this only matter for sources from a network? From my external disk it worked fine.
I'm using Windows 10 Home Build 19044.1706