Thank you very much @tcecyk for this most informative link. I have to say the result of Reboot device with power cord plugged in was no less than spectacular. My 12 month life in photos with /e/ suddenly ran before my very eyes! The majority of “empty files” just filled, and after about an hour, all the remaining “non-displayable” files were left pulsing. After a couple of prolonged sessions over the weekend many naive-user errors were corrected and duplicates deleted. One pulsing file remains (but it displays and it is now shareable, when previously un-receivable).
Thanks again. For reference I will include a plug for this Nextcloud intro. However, I think it is good to read the whole thread. There can be some downsides to installing Nextcloud before you understand the “Cloud” way of doing things. Maybe I did just that at the beginning of my /e/ journey!
Install and connect Nextcloud app to your /e/cloud drive to unveil its true potential