Claw Bramble bodypart

I tried to ask this in chat but I was not able to get an answer

In Keepers League I have 8/10 bodyparts, meaning I miss 2

according to net, one drops from Bosses (Hive Colony)
and the one I miss should be "Claw Bramble" which should drop from stabilized unstable rift from ACT4 onwards

I was unable to do stabilized rift in campaign with my build, but did several of them in maps and got two other bodyparts related to that.
--- Foul Hand (stabilized unstable breach in maps) and
--- Head of Vruun (miniboss rare in map stabilized breach)
but I can't seems to drop that claw bramble, while fought Vruun several times already. And when I returned to campaign I can't find unsable breach at all, guessing that you maybe not get breaches in content that is too low level?

can I drop that intem in map unstable breaches or does "from act 4 onwards" only count as campain and I have to waste time there?