Backend Read (subcollection) document not working

Hi,

I have this variable "companyRef" with the reference of a subcollection document. Company is a subcollection of Economic_group. This variable received value from a custom function that returns this "FirebaseFirestore.instance.doc('$economicGroupRef/company/$companyStr');" As shown in the Debug panel, it has the value "oJgr2dt0ORe5yRikkAUY)|OUP6mzfIXufUuwIRaWhD".

I added an action "Backend Call --> Read document" and set this companyRef as argument. However it brings nothing. See the variable "companyDoc" also in the Debug panel.

Can the "Read Document" call read a subcollection document? Is there a way to fix this?

Thanks.