Broken file uploads

While making a news post, there were uploaded files that would be broken when checking "_Förhandsgranskning_" of the post. Deleting and re-upload worked for some of them, while some were not able to get uploaded directly after being deleted from the list. These took many retries to get uploaded, but it eventually worked out.
Additionally, some files broke after deleting and re-uploading another file.

Unsure how to replicate, wonder if it might be related to many files being uploaded at once.