Experience says mop cleaning usually lasts no more than 5 minutes (I expect it is much less, but never timed it).  My non-expert advice would be to reset everything. If you are using the phone app, power cycle the phone and check again. If that did not clear it, power cycle the robot and base (you will have to unplug the base, wait 60 seconds & plug it back in again --  power of the robot while you are resetting the base - old school wisdom say to power your base up and make sure you can see it in the app BEFORE you power up the robot).  

If it still isn't working, you will need some help beyond my meager troubleshooting background. In that case, best of luck & I hope you will share the fix with us.