@katrin, I don't think I have ever intentionally (or even accidentally) deleted any images I've uploaded. And in any event, from the way the remnant of the sequence progresses, it looks (to me--feel free to correct me) like someone (or some thing) deleted the missing images individually. I say that because the beginning portion of the sequence is present, and as you advance, you end up jumping to the tail end of the sequence, as if I paused shooting pictures and then resumed again later. Except I didn't, and there really did used to be an entire sequence there. I know because I used the imagery to help draw in the roads on OSM. If someone simply tried to delete the entire sequence,with just a few clicks...the begin and end of the sequence would be gone, too, which is why I say it had to be done image-by-image.
Could these missing images be related to this github case I opened?