I see others are having similar problems connecting GF and MC, I'm having the same problem.
When I try to connect a GF to a MC field, I can select the appropriate MC list, but when I select the appropriate GR form, it just sits and spins and will not allow any forward movement.
I'm using GF Version 184.108.40.206.1
MC addon Version 1.6.3
Paypal addon Version 1.4
The site in question is http://www.fryfamilyfarm.org, using a Thesis Theme