Partial reconfiguration - PYNQ Z1

I am having using partial reconfiguration for a PYNQ-Z1 board.

I have been trying to replicate the example in this thread:

But I am running into an issue on how this person got addsubpr_0 as a partition region.

My block diagram looks like this initially (first picture)

and then I create a hierarchy block containing add_0 and sub_0 and name it addsubpr_0. I get an error when I try to make addsubpr_0 a partition definition. The error says: ERROR: [Vivado 12-4865] Failed to create reconfig module as Block Designs type module cannot be made into reconfigurable module

I do not understand how if you’re going to use pr.download() in jupyter notebook if you cannot use a hierarchy block for a partial definition.