I see, M_AXI_MEMMAP is an external port. So, there is no IP associated to it.
I’m not sure the API considered this. There is a newer version of the metadata. You can try to update as shown here
If this not work, you could try to edit this file /usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/hwh_frontend.py
To be
core = self.blocks.get(i.get("INSTANCE"), {})
port = core.ports.get(i.get("SLAVEBUSINTERFACE"))
This is not guaranteed to work
Mario