Sync issue: Lost a day of study data

I use Anki on two windows laptops, and one android phone.

The laptops are used to create cards, the phone for study. They all sync via ankiweb.

For the first time, ever, I experienced a sync process that resulted in my “cards left to do for the day” on the phone went from the current figure (around 100) to the full 235 (the limit setting in this deck). This happened after a sync process.

(Also, the study data for the day from the phone appeared not to get to desktop, it appeared the desktop version’s reality, which was 1-2 days behind the reality of the phone, was pushed to the phone.)

This happened yesterday (Feb 25), around noon Pacific time (not sure when, but between 11:00 and 4:00PM Pacific time).

Was there an issue centrally, or did I fail at some unknown (to me) sequence of events? (I have been doing this setup successfully for over a year.)

Thanks!

Assuming you did not do a one-way sync (“upload”/“download”), it sounds like either the deck or the cards were modified on multiple devices at once. When they’re subsequently synced, Anki keeps the most recently modified version, which can cause reviews or the daily counts to be reset if an older version was modified before syncing.