As mentioned, keep re-pairing-in-place. It may take once, twice, or 37 times. I'm not sure what causes it, and whether I'm unskilled, unlucky, or it is just the way it is. I will say that as bad as that seems, mine have been stable once I got them paired correctly.
The normal stock driver is fine, but I use @kkossev 's most excellent community driver for finer configuration control.
