I think the problem has to do with large note size. I'm marking up a lot of 4k+ sized photos/screencaps. Probably 40-60+ per note.
Evernote is unusable on HDD with notes this large. Each sync will lock up Evernote for 10-15 minutes. Works fine for my text-only notes or on a SSD. No crashing, I just have to wait 10-15 minutes every time Evernote tries to sync (which makes it unusable on a HDD computer). The latest release, however, will crash during sync and lose data.
Original poster said problems were related to photos and recordings. Sounds like the same problems I have run into with large note size.
My guess is that they tried solving the horrendous slow-sync by splitting the file-save format. That fix ended up causing large files to lose data.