Problem in call activity with multiple instances

I am using the callActivity in my project and faced the following issue:

When I use callActivity with multiInstanceLoopCharacteristics feature, the binding of expressions do not work properly, but when I use without this feature, everything is correct.

Here is the XML section of my process definition:

<callActivity id="ubi_id-31a1f64a-e42f-4906-b736-cb9c57ab83c8" name="Call Process" calledElement="XYZ">
    <flowable:in sourceExpression="${m}" target="n"/>
     <flowable:out sourceExpression="${n}" target="m"/>
     <multiInstanceLoopCharacteristics isSequential="true" flowable:elementIndexVariable="loopCounter">

I expect that the result of variable “m” is passed to sub-process as variable “n” and after return from execution of sub-process, the variable “n” from sub-process is passed to “m”. But the result of “m” after return from the sub process is “NULL”.
But When I eliminate the “multiInstanceLoopCharacteristics” section and call activity without iteration ans repeat, the result is correct.

Thanks and best regards,

Which version are you using (there were some changes in this area in latest release)?
You’ve validated that the called process sets the variable n?

I am using version 6.5.0.
I have validated and I am sure that the called process sets the variable n because I can use it in the callee sub-process, but in return and only in case of putting multiInstanceLoopCharacteristics section, the callee does not return the variable m.

Thanks again,

Ok - 6.6.0 is released now, so potentially the bug is fixed there. But a small unit test with what you’re seeing would help a lot for us to reproduce the problem you’re seeing.