Oskarm with Cast while Channelling support socketed in

While Oskarm on its own properly applies Assassin's Mark when hitting Rare or Unique enemies, this breaks down when you socket in the Cast while Channelling support gem (Assassin's Mark doesn't get applied at all). However, if you link that CwC gem to an another Assassin's Mark, Assassin's Mark gets applied as expected.

Without Oskarm, I tried linking together Cyclone + CwC + Mark on hit + Assassin's Mark - the mark never gets applied, just as in Oskarm's case.

This odd behaviour probably stems from Oskarm having an internal Assassin's Mark + Mark on Hit combo, which is affected by the socketed gems, but socketed gems aren't affected by the internal Mark on Hit.

At least from the Oskarm's description, I wouldn't really expect this behaviour. Perhaps Oskarm's Mark on Hit shouldn't be affected by the socketed gems?

Well, yes - that's obvious from the behaviour. Question is, whether it's any good to have this behaviour - I can't think of a scenario, where (at least in this particular case) having built-in mark on hit supported by socketed gems would be useful.

I do. I don't want it to be affected by the socketed gems, though.

Oskarm's description says it triggers the mark when you hit a rere/unique enemy and that's what I expect it to do, regardless of underlying implementation or socketed gems.