Flow isn't updating value when called as subflow

I have a flow (image attached) which update the "completed" status of an assignment entity. I can see the data changed in report when this flow is executed manually by passing the assignmentId (via debug in Decisions studio). But, when called as a sub-flow in another flow, it fails to update the data. It doesnt throw any error but the data isnt changed as expected.

The following is in response to Wills reply email (sorry, I couldt find that reply in the forum):

In the original flow, I have send-email steps on each path and it is confirmed that execution took the singular path at runtime. I just removed them for better readability when posting it.

I was wondering whether it is something like a scope restriction in Decisions which I am not aware of (e.g. whatever changes made by the subflow is reverted back by the parent flow – like changes made in sub-routine to a parameter is lost when returned to caller-routine when the parameter was passed as a value not as a reference).
[i]edited by kyaw kyaw htat on 8/2/2019[/i]

Hello, lets discuss your issue in more detail in as support ticket so we can better understand what you are looking for. I will go ahead and opened up a support ticket on your behalf and you will be notified through email once this tickets been created.