Import and run 2 level deep AIP functions Developer Console API

Is this a bug or some configuration error?

I have three AIP functions:

  • Main: Moderation
  • Sub: Moderation_rule_01, Moderation_rule_02
  • Helper: FormatOutput

I call Moderation_rule_01 and Moderation_rule_02 from the Main Moderation function. I call FormatHelper from Moderation_rule_xx.

When I add the Main function in the Developer Console, it offers to import dependencies. BUT ONLY for the first sub-level; it does not offer for the second helper level!

If I call the API using the user token of the AIP-creating user (from PHP, not via the SDK), then the helper functions run as well.
If I use a service user/OAuth authentication, then Palantir returns an error.

Question:
Is this a bug or a misconfiguration?
The functions run with project scope, the service user is added to the project, and has access to the AIP files.