"Invalid Property on Card" not resolving via recommended "Check Database"

Hey y’all - ran into an issue with a sub-deck that notably didn’t pop up until I rescheduled/reset a chunk of cards to new. For context - I had done a few cards from a musculoskeletal theme last year basically just to get used to my Anki as a whole, but ended up suspending them shortly after with the intention of coming back to it when the time came. That time is now, and so I went to unsuspend the cards and, of course, they now had very long intervals on them from the time I spent away from them. So anyway, I reset them.

Since doing that, the occasional card from that batch will provoke a message reading “Invalid property found on card. Please use Tools>Check Database.” Did that, coding said that invalid x (#) of invalid properties were fixed, I figure I’m good to go. But then when I finish up, I go out to my deck and there’s a huge chunk of “recovered (insert random long number here)” decks on the main page, which ultimately appeared to be decks I had deleted a long time ago. I delete those, but then when I exit out of Anki & try to sync, it says my deck is now out of line with Anki Web. That was of course stressful/anxiety-provoking, but I ultimately uploaded my “new??” deck to AnkiWeb.

However … when I came back to do more cards, many cards from that same deck once again started giving me this message again. Moreover, coming back to those same cards today, I’ve noticed that the problematic cards also have seemingly corrupted intervals (I’m only given the option of “again (<15 min)” or “Good (2d)”). Not sure if this is related to the aforementioned rescheduling, but please let me know if anyone has run into this issue before and knows what to do. I am going to try running the same solution again but this time without deleting any recovered cards (though I don’t see why that would help + it’s going to make for a nuisance on my home page). Really can’t think of any other solutions, and can’t find any online.

Thank y’all in advance for any and all help!

The DB check is reporting a problem when it shouldn’t - I’ll fix this in the next update. But I’d recommend you update to the latest Anki and switch to the new scheduler instead, as it should prevent this from happening, and comes with other fixes: The Anki 2.1 scheduler - Frequently Asked Questions