GNS 530: "MSG... MSG... MSG... Set course 079"
Me: "Umm... the MC60 digital localizer automatically tracks the desired course. It's really advanced."
GNS 530: "MSG... MSG... MSG..."
Me: "What is it this time?"
GNS 530: "Set course 076"
Me: "Like I said last time, the MC60 is already tracking that course. Turning the OBS knob does nothing, you silly GPS."
GNS 530: "MSG... MSG... MSG..."
Me: "Oh goodness gracious me!"

So, the GNS 530 flashes a MSG thingy some time after each waypoint if the OBS doesn't match the desired track. I guess it's reminding you to keep a clean cockpit. But with the MC60, you can't change the NAV1 OBS unless you:

• sync the heading bug to your current track
• set HDG mode on the AP
• switch the CDI to VLOC mode
• turn the OBS knob on the MC60 to match your desired track on the GPS. by default it's probably set to something like 360.
• switch the CDI back to GPS mode
• set NAV mode on the AP

If I do that immediately after I pass each waypoint, I'll avoid the dreaded MSG... MSG... MSG...

That's a lot of work so I wrote a .lua script that does it for me every time the desired track changes (it just reads (A:GPS WP DESIRED TRACK, degrees) and pushes it into (>K:VOR1_SET) if the CDI is in GPS mode but the GPS OBS is not active). I can't turn off the MSG thing in WT's GNS 530 but I can at least work around it.

But I'm curious if that's the expected interaction between the MC60 and the GNS530. Should the MC60 in the sim do the same workaround to keep the GNS 530 from flashing that MSG indicator?

I haven't tested with the GNS 430 or the GTN 750 so I don't know if those units have the same behavior or not.