My display is also very wide, but the “Create Event” fills the width of the screen entirely, and I can only drag the box up and down the screen, not sideways.
Also, I think the bug you’ve found is marginally different to mine. If you look at my screen shot the dropdown list is burred behind even the WP sidebar menu, whereas yours is “white” and is on top. Also, mine is 100% reproducible, sounds to me like you had to fiddle a bit to get it to play up.
I’ve also now tested this on my android device, and it shows the same behaviour as in my image. Quite frustrating, and I simply can’t wait for someone to fix if it’s not going to be within the next week (given there’s xmas in there, this is probably unlikely)
I’m going to slurp my site into a VM, and see if doing a re install cycle of either WP-Athletics, or attempting a rollback is going to help fix this issue.
Thanks for your help thus far though. I appreciate just knowing that it’s been registered.