I would be interested to hear Urs/Flarm’s, or the PF people’s,
reaction to that.

To my simple mind, for you to get an alert, your PF antenna and the
glider’s PF antenna both work on line of sight, so each has to see the
other. It should not be a one way street.

I suppose it is possible that in one direction the signal was just
strong enough and/or not too badly attenuated, and the other less
good. What do the experts say?

Chris N.