STAUTHTRACE not returning values for objects

while determining a role for a service (as in an interface service / SPROXY) user using STAUTHTRACE, I came across something unusual.

the services (6 in total) are called externally and handled by one user. when checking STAUTHTRACE, I can see that it does show the authorization objects that are checked.  however, the values for these objects are not shown.

when tracing the same user and the same services in ST01, I am able to see the values.

this is what part of the trace looks like in STAUTHTRACE:

and this is the same part of the trace in ST01:

if I change the user type of the user from communication to dialog and log in manually, the values do appear again in STAUTHTRACE as well.

it seems that only when the services are called externally (PI), the values go missing.

has anyone come across this issue and knows what to do about it?

thanks for your help!