Media Browser Shows No Files

Since I moved my Photos library to an external 1TB SSD none of my Photos files show up in the Media Browser in Keynote or Pages. The SSD is formatted as an APFS volume per Apple recommendations. My Photos Library is set to download originals. This is my system Photos Library. The Media Browser says "No Photos." My Photos Library used to reside on an external RAID array that is formatted as Mac OS Extended (Journaled). When the library was located on the external RAID array the Media Browser worked fine.

One thing that occurs to me is that it could be a problem with the APFS formatting, but that is also how the internal SSD is formatted, and I wouldn't expect Keynote to have difficulty reading in files stored on the internal SSD. I'd appreciate any insights that you can offer. As it is now, I have to export images and then drag and drop them into presentations, which is a royal pain.

I don't want to move the library back to the RAID array, because I'd like to be able to take it with me when I'm working mobile.