I’m using zwift on android with a tacx Vortex. Doing the beginners ftp builder programme, today’s tempo workout was fine in the recovery sections but as soon as the effort went up, the measurements seemed to go wrong - the cadence went up to 160(!) - counting it showed just under 100, and the power measured was up to 100 watts lower than the target. The erg turned off in the last effort.
Any ideas what could have been going on or what I can do to get it right next time?