This has happened to me on every ZA workout. Wattage, cadence are all normal, but speed varies widely. One moment I’m riding at 30kph next second virtually stopped with no inclination changes. I usually end up in a small blob with 10 or so riders all doing the same thing, way behind the main group. Very very annoying.
I’m running a tacx neo t in erg mode, ant+ connected, windows 10, wifi @ 20mbps.