@SkyVagrant4490 @HalberQuacky @geoffda thanks for your help last night. I have eventually resolved the issue with the nav data, but unfortunately there are two possible solutions and I’m not sure which one did the trick.
I did an uninstall/reinstall of the 737, which didn’t resolve the issue. But i realised that when I did that, and restarted the sim, it didn’t take the usualt 10-15 minutes “first time start up” of the 737 - so clearly a straight uninstall wasn’t really uninstalling everything. I also noticed that in the install process, it automatically installed the navigraph 737 data.
So I unisntalled again and this time deleted every folder I could find that related to the 737 - specifically a couple of folders in the C:\Users\username\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe folder and in the community folder.
First off, doing that removed the 737 nav data from the Navigraph Navdata Center.
I then reinstalled the 737, which again reinstalled the Navigraph navdata automatically, and this time, when I started up the sim, it did take the 10-15 minute start up and the nav data was working.
However, in the middle of all that, sod’s law, the nav data cycle changed to 2205! So the issue may have been resolved by that nav data update - although my money is on the uninstall+delete remaining folders doing the trick.
I’m curious about how the PMDG 737 installer knows to install the Navigraph up to date data when it installs. I can’t remember exactly how (or even if) I linked the Navigraph data to the PMDG 737 on first install - does anyone else remember how that works?
Anyway, sorted now!