I am lost for words!!!!
I am currently on the 11 (towards Pennywell) and a stagecoach employee also boarded the bus had a but of a confused look asking the drivers' duty number etc... and it wasn't the one he was expecting. Anyways after we left Borough Road and approached the bus stop for Vine Place the employee asked to see everyone's tickets and passes. Not sure why he didn't wait until after the stop as he was blocking everyone get on/off. 
He visually looked at people's paper tickets and scanned electronic ones on the app, Stagecoach Smart Cards & concessionary passes.

It has been like 2019(?) as the latest possible time since I've seen a ticket inspection on a bus.