Cannot move cards in or out of a specific list

[Savanna Timofei]

We have a list called "done" that is failing to move cards in or out of. It's not 100% of the time but for 2 days its been approx 90% of the time. 

The list did have approx 950 cards in it so assumed that was the issue. we have archived 700 or so but the issue still stands. 

Every other list is fine and we can move cards freely. 

We get an error saying failed to move card.