After updating to watchOS 5.2, brightness is stuck on 'low'

Yesterday, 27 March 2019, I updated my watch [series 2], phone [6S], mac [Mini late 2014] and AppleTV [4K] — my watch is now on 'low' brightness. I have tried to change it from the watch as well as from the WatchApp on the phone. Although the sliders on both devices move, the watch brightness remains on 'low'. I have also rebooted all devices. No difference. However, if I do a screen grab on the watch, it comes out at full brightness [the attached pic is a simulation]. PLEASE HELP.