I found another bug. This is on the current stable ios app.
So I added 10 new cards and before engaging with them I backed out the main menu and did an Advanced Study.
This study then zapped my upcoming reviews count to 0.
Then when I went back to do a normal study session and added 10 new cards… it added the next 10 cards (after the original 10 I added but have not seen.)
So Skritter thinks I’ve studied those 10 cards or they’re lost in the ether somewhere.