I'm using Trello in collaboration with a client. All of a sudden I can no longer add checklists to a card on her board. I used to be able to do this without any problem, and I can still add checklists on my own boards. But when I'm on her board, I can only edit checklists that are already added to a card. I've tried opening cards that I've created and had previously added checklists to and experience the same issue: I can edit the checklists I already created (add new items or change words on existing items), but I cannot add a new checklist.
When I click on the "Checklist" button, nothing happens. No error message, no menu. Nothing at all.
The strange thing is that while trying to figure out and test on different cards, I had one card that let me add a checklist. I deleted that checklist, and then tried to add another one, and it wouldn't work at all.