Bug/Issue XNB mod seems to be corrupting my save files

Does anyone know why an XNB mod would corrupt a save? Two out of my three save files were missing from the Saves list (female farmers disappeared, male farmer okay - relevant?), but have been restored after replacing all the original Content files. Also, when following the troubleshooting guide, replacing the SaveGameInfo for those profiles did make them show up in the list, but I was unable to open them - the game just looped back to the intro screens. SMAPI doesn't affect the saves.

I haven't done any troubleshooting yet, I'm happy to add them back in one-by-one to find the culprit; I'm more curious about what could be causing the issue so I can avoid it with my own sprite modding.

Thanks in advance!

 

An XNB mod can certainly make a load fail (e.g. by breaking a data file), but I don't think I've seen them make a save slot disappear outright. I can help you look into more deeply, though it'd be difficult to do over the forums; come ask in #modding on the Stardew Valley Discord if you're interested.