Hey @Charles,
the problem actually is fixed by switching r.HairStrands.SwapType to 3.
In case you still need a repro project, I will create a little sample 
Thanks so much!
Edit:
No longer able to reproduce this since 5.4.3. Will try again, as it has been some time since I tried to deal with this
I might still have an older project lying around where this is happening. Let me know if you are interested.