isAction is not working in MST

[BanShan-Alec]

Intended outcome:

isAction can not work correctly in mobx-state-tree

Actual outcome:
When I use mobx-state-tree，I need judge a function is mobx action, but isAction always return false, I don't think my code is bad.
So I report this bug.

Now, I use a Private property _isMSTAction to resolve this bug, but using a Private property is not a choice for clean code.

How to reproduce the issue:
https://codesandbox.io/s/mobx-state-tree-playground-forked-yxhy6p?file=/src/index.js

Versions
"mobx": "^6.9.0", "mobx-react-lite": "^3.4.3","mobx-state-tree": "^5.1.8",

[urugator]

MST's action isn't mobx's action, it's some abstraction on the top of it. You should seek help in mobx-state-tree repo.