RPM issues Tacx bushido staying in mid 60's?

Hi, first post so apologies if this is in the wrong place??
I’ve had a issue on the last couple of rides on Zwift where the rpm showing on the screen stays in the mid 60’s regardless of how fast I am pedalling?
I’ve checked the firmware on the trainer is up to date, in the Tacx utlility app, everything seems good, the RPM seems to rise and fall like it should as I pedal. My internet connection is good but its really starting to annoy me! On a couple of meet up rides, I was pedalling like mad and getting dropped out the back.
only been on Zwift for 5 months and never noticed this before so could it have been the recent updates that have thrown something off?

Help please?

Thanks

Tim Higgins