All my cards go into one stack

Hey,
I’ve got a problem with creating new cards. Each time I’m opening a stack to add a new card, this card is always going into one particular stack, even though I selected a different one. Of course I can shift them into the right stack afterwards, but that obviously takes lots of time. Has anyone had this issue before? (I’m using the desktop version, but tried out the web version and had the same problem)

The first place you can check is the top of the “Add Note” window. Are the cards created from your notes going to the deck you choose there, or some other deck?
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If they are going to some other deck (or some of the cards are, at least), your note type probably has a “Deck Override” set for 1 or more of the cards it makes. Card Templates - Anki Manual