Following up. In my case, when I was trying to intercept ILS RW05, it was indicating BKCRS on the right side of the PFD, leading me to believe that this was a Back Course ILS, which I'd sort of heard about but have never tried (no, I'm not a RWP yet). The Locator bug was on the right when I expected it to be on the left, so I decided to switch to RW23
The conditions were LIFR, so I decided to switch to RW23, but also got the same weirdness. I somehow managed to land by hand-flying the LOC/GS bugs (Flight director was still directing me away from the approach course, so AP was no help). (If real-world, I'd certainly have diverted.)
Did this same scenario a day later, same result.
Did it yesterday, but realized previously that I'd tuned the ILS on NAV1, but had the Glasgow VOR tuned on NAV2 (FO side) just for additional DME data. This time they were both tuned to the ILS, and everything worked perfectly, both runways.
Unsure if this is expected? With JustFlight, I'd be 90% sure this is by design and not a bug.
I'll try this again tonight, maybe switching NAV2 between the ILS and VOR to see if this is really the cause.