Inconsistent thumbnail creation with IIIF

I’m working on a new project on Omeka S version 4.0.4. I’m using the csv import module to create Media with IIIF images. It’s mostly going smoothly, but I am baffled by inconsistent appearances of thumbnails. 95% of thumbnails will generate correctly, but then one will seemingly randomly not be generated. The image itself does appear in both the front end and backend if I go to it directly, but the thumbnail appears nowhere. Is there anything I can do to fix this?

Example of what this looks like, with images that were all ingested at the same time and have no difference in metadata:

Is the problem reliably with particular images? So for example, if you go to insert that image used by Page 324.3 as a new item, does the problem persist every time? Or is it a more random problem where the same image might work or not work, depending?

It’s more random. I re-added 324.3 and this time it appeared correctly. My best guess is it’s just some kind of hiccup with ingesting a lot of images at once–is there any way to refresh the thumbnail creation of certain images without having to re-ingest?