When viewing a deck and choosing the menu to move a certain card to the sideboard, it adds that card to the sideboard but does not disappear the row from the deck. It does remove it from the stored version of the deck so that if the page is refreshed, it is only in the sideboard.

This is in contrast to moving a card from the sideboard to the deck, where the row on the sideboard is removed without needing to refresh the page.

Sounds like a browser specific issue. I have not encountered this myself.

Fixed now. Thanks for reporting.