After selecting, say, 2000 waypoints, why does Basecamp take foreverrrrrr to change the symbol type?

I added artifact locations as waypoints in my Garmin Montana 600 series GPS.  I download it to Basecamp to a List and decide that I want all the waypoints in the List to be a black dots, not a green dots.  In basecamp, I sellect all waypoints and open, choose the symbol I want and hit GO and it takes a very, very long time for Basecamp to convert them.

Has this issue been addressed?

Thanks