Normcore tamping station and Barrista Pro portafilter fit?

The normcore tamping station (54mm vers) just arrived. It looks lovely, but I'm trying to figure out exactly how to place the portifilter.

The portfafilter I'm using is packaged with the Sage/Breville Barrista Pro and had the more curved splitter, rather than the smaller nozzles of the Barrista Express/Bambino (which look like they would slot directly into the holes in the portafilter holder).

The only way I can see to fit the portfilter at all is to rest it on the smaller indents circled in the second photo. It might be secure enough to tamp, but it can also forsee the portfafilter sliding back, and one side falling into one of the holes. All the weight is also resting on the nozzles, which I imagine could dent the silicone pretty quick.

There's a couple of attachments, but none seem to fit the portafilter. Am I missing something?