I just filed a ticket on Zendesk about this but I thought I’d write here as well in case someone is having the same problem as I did.
On my setup I have multiple monitors including two small ones, 800x600, that I use for the PFD and MFD. Yesterday I enabled HDR on the main monitor and in MSFS just to see how it looks. I started up a flight in the DA62, undocked the PFD and dragged it over to one of my small monitors. Then, as soon as I double clicked to expand the window on that monitor the sim froze.
I recon this has to do with the fact that the smaller monitors don’t have HDR support, when I turned of HDR it worked again. So my conclusion is that one should avoid HDR in a multiple monitor setup unless all monitors support it.