I think hummingbird minify has broken gravity forms

I think hummingbird minify has broken gravity forms. Example page is portridge.uk/template - this has a gravity form embedded but displays as blank page.
I've been working on hummingbird and since then the forms disappeared. I also did wp update (not a major one) just from 4.7.3 to 4.7.4

I've enabled support access.