Smart Keyboard Intermittent Issue

iPad Pro 10.2 and Apple Smart Keyboard. Been fine for a year or two since new but now randomly switches from Smart Keyboard to on screen mid sentence about 75% of the time. Works again after reboot but can happen again in 1 minute. Have cleaned (several times) the points on both the keyboard and iPad itself to no avail.

Anyone else managed to resolve this?

cheers,

Ric