I've been staring at this for quite a while, thinking that surely 'partition_group' is spelled wrong in one of the two places, but it's not. I've tried a number of changes to the query, deactivating / building / reactivating partitioning, etc. No matter what I do this error persists. The name, the type, and the position of the partition are all as they should be. The error message is telling me that I MUST do precisely what it's telling me I did do.
This is from sqlexecutor within a Python recipe, but the same error occurs if I try to use a SQL query directly.