I did a few audio interviews for a podcast and experienced the same phenomenon, but it hadn't anything to do with the actual recording. Instead the convo became more relaxed once I'd announced the end of the interview into the mic. It's simply performance anxiety that we all experience to varying degrees. I think a big part of it is to set up the tech and then leave it alone and try and be yourself. That takes practice. But if you're tinkering with tech while you're talking, I'd give up on any chance of your interlocutor's feeling relaxed. That means you have to practice with your tech too, so you know that your know what you're doing. Forgetting to switch on phantom power to mics if you need to - that's a biggie. Or your camera's on standby, not record. Or your lens has a big sticky mark on the front that you've not checked. So give yourself more time than you think you'll need to set up and check everything. Have a check list because pressure will make you not think of everything and you'll kick yourself for that later.

For my interviews I tried to set up a comfortable location and think I managed it. Also provide refreshments. And once you start, try and relax yourself, be yourself and try to listen rather than think too hard about direction. That's another thing that comes with practice. I'm sure with your public speaking experience Rod you'll not have any problems there, but it's worth bearing in mind. Relax, listen, engage. And most of all, have fun!

Love that M50 by the way. I'm toying with the idea of one of them or a wide angle lens for my Sony. The M50 is cheaper!