This seems to me to happen when I set defaults from the "Front Office" page, which is the logical place.
It SEEMS to me that it happens less frequently or not at all when I set the defaults from the popup after I hit schedule. In other words, wait until the aways can be set, hit the first scheduled game from the next series, then set the defaults from that screen.
I could have missed changes that have happened, but this seems to be more reliable, though the opposite really should be true.

Dave N