I have an 8t 2.0 rtr with the included spektrum dx3s.
The rx voltage and temperature telemetry comes through just fine, but the rpm/speed function doesn't.
The radio just sais "no signal"

Has never worked.. any ideas on why?
I have not unplugged anything or tampered with anything.

Any advice appreciated.

cheers

Do you have the rpm sensor hooked up?

I haven't taken out the radio tray to have a look, but there is a wire plugged into the rpm telemetry port on the rx so I would imagine so yes.

Think I will remove the radio tray and see whats happening.. on the link you posted you can see some chrome and black stickers, what do they do exactly?

Seems I just answered my own question, I will need to place a reflective sticker on the rotating member.

Yes, that is correct.