Moto E4+ 7.1.1 - Call Swipe Just Disappeared...?

[AC Question]

Happy as Larry with my new Moto E4 Plus (£150 - what a bargain) until it went wrong. I cannot now easily accept inbound calls with a normal swipe across (there is nothing to swipe). Now I have to go into the pull-down menu, touch the call notification panel - then answer the call (if they haven't hung up). Any ideas what that might be...? Notes; I have Truecaller installed (was fine together). I have tried a restart and uninstalling/ reinstalling. Still no go. HELP!