After several attempts I gave up on the bluetooth - it seems particularly poor on the Intel NUC. I set up a mouse with the Logitech receiver dongle, ran a tune and didn't have any issues, so thanks for that suggestion!

If you are using a SmallIR then why is there a KAT500 antenna tuner involved at all? There is no antenna tuner required with that antenna. That could very well be a major part of your problem.

The antenna is sensitive to elevation and radial setup, and there is a limited amount of adjustment that ...

Regarding my antenna and feed line:

My antenna is a SteppIR SmallIR mounted on my roof peak. It is fed by ~75 ft. of 400MAX coax from DX Engineering. All interconnects between radio, amp and tuner are 3ft. runs of RG400, also from DX.

I've fiddled with this a bit more and it does certainly look like an RFI problem. I have never had issues during transmit. After a bit more experimentation I noticed that the keyboard and mouse behavior gets very wonky (wired USB), which is why the UI on the whole system doesn't respond correctly. I ...

I am using an ANAN 7000DLE MKII with embedded i7 board. I've had a lot of boot issues with that embedded board which was fixed by some carefully located pieces of electrical tape, but that's for another thread. My main issue is that the UI locks up and gets stuck in transmit mode when using TUN. I ...