Simscape Multibody - can't connect blocks

I recently installed Simscape Multibody. When I open a new model, the Multibody blocks only show 'SimscapeMultibody' and I'm not able to connect any of them - they don't have any input or output ports. I don't have this issue with blocks from the base Simscape library.

I've tried reinstalling Multibody but I'm getting the same issue.