>>/1289/
Ah, for files that seem to be malformed, there are two answers:
1) The file might have been corrupted. In the 'file maintenance' system, there's a set of jobs called 'missing/incorrect' that scan for this. These jobs are expensive though (they have to load the whole file from disk), so don't add them for all files. Try to target with a tag search or system:hash search just to hit the file(s) you think were affected.
2) The file might have once been supported but now is not. This is rare, but a handful of truncated jpegs and other borked files used to load in hydrus until I turned some safety rules on (the lack of safety was causing crashes in some systems). Best answer here is to just delete the file, or export it, run it through a load/save cycle in Gimp or Photoshop, and then reimport the fixed file. Some boorus just have jank files unfortunately.
If you like, you can post that image here (if the site can accept it), or zip it up and email it to me, and I can have a look. But if it is private, no worries.
These bad files being from the same session makes sense that this was a one-time event. I would still suspect it is a hard drive issue, but it could be something else, especially since crystaldiskinfo was good for you. There's a very small chance that if you have a program crash or other hard turn-off that the client can become unsynced, but that typically ends up being the other way around: the file gets added to your hydrus file storage, but the client isn't aware of it. The client can lose up to 30 seconds of database work if it ends non-cleanly.
Let me know how you get on!