A couple of ideas:
- I assume you have adjusted the sample rate. I had this issues with another Behringer product and fixing the sample rate fixed the problem. https://forum.audacityteam.org/t/asio-problems-on-xr18-solved/59033/1
- What happens when you do Shift-Record?
- If you have an ASIO driver for this unit, it now much easier to build Audacity with ASIO support. See: https://forum.audacityteam.org/t/asio-support-in-audacity-2-4-2/57964/13
I hope this helps. 