The distance column was working for me prior to adding a second site.
I had found this thread:
where someone else asked basically the same question, and @esmathews referenced this was known behavior and was “being worked on”. Also gave the explanation that multiple sources made distance calcs “interesting”, which makes total sense if the data in question could have come from either site.
I’ll wait a day or two and see if FA gives up listening to/for my second site, but I’d expect as long as it thinks there are two potential feeders, it won’t bother trying to calc the “interesting” distance. I might just turn the second site back on - I don’t expect it’s feeding any data the first site isn’t already getting (given its superior antenna and dongle), but I suppose it can’t hurt.