[Remote API] List of potentialOwners is always null

Description of problem:
It is not possible to retrieve Potential Owners of the Human Task using native remote client.

Version-Release number of selected component (if applicable):
bpm 6.0.3+rp1 applied

How reproducible:
always

Steps to Reproduce:
1. Deploy attached kjar into business-central, it includes process with human tasks which has following expression under actor field: "anton1,anton2"
2. run client
3. The List of potential owners is null - in UI, this list is correctly populated

You may need to alter the Users (either or server or client side, or both..)
I am using "anton1" and "anton2"
Actual results:
The list of potential owners retrieved through remote client is null

Expected results:
The list of potential owners retrieved through remote client contains potential owners

Additional info: