I'm running M2.1.5 and there seems to be a bug when update associated product stock quantity.
I found similar issue reported here but I can't find the commit/PR that fixes it.
My issue is a bit different than the one report above, which is few associated product still updated. i.e: 50% updated
other fields such as price, weight work well.
Any one has any idea how to fix this or finding the right commit in 2.2 to back-port to 2.1 ?