I have a tacx flow that I am trying ot calibrate.
It keeps telling me too loose and to tighten but I cannot tighten any tighter
DC Rainmaker has some hints re Flow calibration in his review.
What size wheels & tires?
Which frame mounting holes (upper or lower) are you using?
How are you calibrating (TACX Utility App, TACX Training App or on a device eg Garmin etc?
My related experience below but might not be your problem ?