Hello
I hope my story may help.
I originally bought a Thinkware F800 Pro Dashcam for my CT 200 and had it installed professionally through a company recommended by the RAC. I have had no problems with reception even though it is an early car(2013 F Sport).
I purchased the same dashcam for my 2016 NX F Sport and had it professionally fitted and had continuous signal drop.
I contacted the installers who came back and installed the ferrite cores still to no avail.
The installer was very efficient and investigated the problem and decided it was the plug in lead interfering with the Dab aerial.
Eventually the company asked me to try another dashcam that didn't have a plug-in wire into the camera but rather one that had it's own prewired "screened" loom.
They exchanged the unit for a Thinkware F790 and the problem was resolved.
I hope that's an understandable explanation and hope it helps you.
May be worth looking on the RAC website but sadly this wont help your current dilemma having already bought a Dashcam!
I have to say that I do like the Thinkware dashcams, as they have the benefit of many features including verbal warning of speed cameras, their distance away, and the legal speed limit.
Regards
Ray