They replied to me today and I got the same response - the button was removed because people were concerned raccoons could open it. They did say they are likely adding a new feature to a future system upset that will let you cover the sensor to open and close, as a replacement to the button. They also said manually pushing it up/ down should be OK to do. I feel like a raccoon is just a likely able to do that as figure out the button.
As for it not opening, they had me uninstall the app and reset the device. We'll see if it works in the morning, but not having high hopes. As you said, the closing at sunset works and using a scheduled time works, which I guess is fine.