I've had one disable zone for the winter and i've ticked the slider to "enable it" but the zone still has and exclamation mark and says it's not scheduled. Yet another frustrating thing in the software that is not intuitive.
I would double check that the zone is chosen in one of your schedules. If you still have questions after checking please let us know. If you private message me your username I can take a look.
I was able to get it turned back on immediately using the web app. No problem. It's the phone app that buries everything in impossible to decipher locations. Looking forward to the phone app reboot in the spring!