Getting Expression error like An error occurred while applying the context for the MDS FBM Case related action [identifier=1,356]. Details: Could not cast from Check_testRequest?list to Dictionary. Details: CastInvalid

Hi 

In Record related action context i have passed like this  to get request id details from query 

rule!Cust_QE_getRequest(
requestId:rf!requestId,
returnCastedData: true
)

when i am trying to access related action getting error like below could you please suggest on this

An error occurred while applying the context for the MHK Data Case related action [identifier=1,356]. Details: Could not cast from Check_testRequest?list to Dictionary. Details: CastInvalid