I'm having a similarly frustrating experience, the first unauthorized edit we noticed was our check-in time was suddenly 8a-10a (previously 3p), which neither the owner nor I made. And doesn't make any sense because check-out isn't until 11. I reached out to support and they said they didn't have the ability to make said changes, and denied an update which may have caused some listing info to be reset.
Yesterday I was making changes to the nightly prices, deleting last-minute discounts and increasing the cleaning fees. Today none of these changes were reflected (yes, I hit save and double-checked that the edit was active). We had a last-minute booking that received a discount AND when you look on Airbnb as a traveler, one of our listings has a price we've never used ($57, instead of the $75 we're listing it at).