I’ve returned to using Anki after ~3 years of inactivity, and have since run into the same weird issue (bug?) twice, messing up the intervals/due dates on a small subset of my cards. It seems random to me and I am unable to reproduce the issue, but I’m afraid it could happen again and am unsure about how to deal with the damage done.
First off, I’m using the newest versions for both Anki on a Win10 machine (to manage my decks) and AnkiMobile (to do my reviews). I’m also using the latest stable schedulers. None of my add-ons interfere with the scheduler and I haven’t changed any relevant settings on the affected decks/cards since my return.
To deal with the huge amount of reviews after being gone for so long, I’ve resorted to using filtered decks. I’m filtering some tags and bunch of cards sorted by ‘decresing interval’ to at least deal with the easier cards before tackling the harder ones, then rebuild the filtered deck every day.
One day, upon looking through my decks, I realized that some notes were missing, and I found a couple of ‘(deleted)’ entries. I wondered what happened, but managed to restore them by initiating a database check. A new deck, named ‘recovered’ with a random(?) string of letters appeared, and I sorted the cards therein back into their respective decks without really looking at them. I was also prompted to do a full sync, but didn’t think much of any of it. I figured that some data must’ve become corrupted, but Anki managed to restore it, so everything was alright at that moment.
However, a few days later, the issue occurred again and this time I noticed that the intervals on many - or possibly all - of those cards were completely messed up. Some cards that were created in 2014 (and are not new cards) are suddenly due in 1954. Several leeches - that I just failed a few days prior - have an interval of 101.4 years and are due in 2090. Some notes that I’ve already reviewed and pushed years into the future are back in my filtered deck that should only have due cards.
I have no idea what happened to those cards. It’s completely inexplicable to me. I tried to find anything about the ‘recovered’ decks that Anki generated, but wasn’t successful. It doesn’t appear to be anything that other users have reported before.
I can probably find a way to deal with the broken cards, but I can’t have this keep happening. Is there anything I’m doing wrong or a solution to fix this? Any help is appreciated. Thank you.