Unable to edit my whiteboards

I have a Zoom Pro account, and I can't edit any of the three whiteboards that I created a little over a year ago.

I had experimented wit the whiteboard feature outside of a meeting to familiarize myself with it, and then when I tried using it live with a client, I found it clunky and awkward, so I decided to go with a Google Jamboard instead.

However, I kept the whiteboards in my account, thinking I might give it another go.

Now, I can view my old boards but I can't edit them. My understanding was that I could continue editing 3 boards with my current plan. What's wrong? The whiteboard feature is useless to me at present. This is very disappointing.