Tacx NEO 2T - Issues

Hi I have recently bought a Tacx Neo 2T trainer and set it up.

My bike runs an ultegra gear set and I have tried with a 105 cassette and also an ultegra cassette on the trainer. Both the correct speed (11).

My issue is when I come to ride my bike.
When I pedal forwards everything is ok.
However when I begin to coast/free wheel, my chain drops down and is no longer tight. When I have had the trainer on working through the mains power, this obviously causes issues.

Hopefully someone can advise/assist me with the issue.

Thank you

Could be your chain is old and stretched? How many miles are on your current chain?

did you install the cesette correctly? check if your freewheel hub is not stuck or rubbing on the frame.

I have Neo 2T with Ultegra 11 cassette. Have you added the 2 spacers btw the hub and cassette? This is not obvious in the documentation. before I did that, something was rubbing/stuck. After adding the spacers, all is fine