GPS unreliable after reimaging

Been running flightbox with Avplan for the last few months and generally been pretty good. My flightbox is single band, without the AHRS addon and using the external GPS (G-Mouse, not VK-172).

About two months ago, my flightbox became corrupted and I had to reimage it. Since then, AHRS has been working fine but I’ve noticed that the GPS is now quite unreliable. About every second flight it doesn’t get a lock or detect any satellites. I’ve tried resetting with no luck. I’ve tried different positioning within the aircraft as well as standing out in the open on ground with no luck. There also haven’t been any satellite coverage outages on those days.

Anything different I should consider? I might reimage again to see if that helps. Should I use the latest beta to help?

I am planning a cross country trip soon and need a bit more reliability. Would upgrading to the AHRS unit help improve the reliability?