FileSideload: Sometimes derivative images missing

When adding multiple media files to an item via File Sideload (i.e. clicking on the Sideload button multiple times, thus adding multiple Sideload media blocks before saving), for some of the medias no derivative images are being generated.

Original media file types are all jpeg and the topic even concerns original file sizes < 1MB, whereas following bigger files are being processed.

When adding the media files one by one, derivative images will be generated as expected.

The error log reads:
2019-10-24T08:21:47+00:00 ERR (3): Command “/usr/bin/convert ‘/homepages/[…]/htdocs/archiv-sideload/004__MStock_16051839.jpg[0]’ -auto-orient -background white +repage -alpha remove -thumbnail ‘800x800>’ ‘/tmp/omeka5KGExZ.jpg’” failed with status code 1.

File Sideload 1.3.0 with Omeka 2.0.2