Shuji at Zwift HQ here. I looked at your server log history and see your Zwift Ride controllers are still on the factory firmware version 1.0.0.. Please update to the latest version 1.2.0. Here’s how. That should improve any button functionality, but may not address the workout interval skipping.
I see you’re a very experienced Zwifter. Is this workout file one you’ve used before, or one that’s new to you? I suspect the way the custom workout file is built might be the issue. There are some things to know about those workouts we’d like you and your coach to review in this support article and also this one.