OAuth 2.0 Authorization Code Grant problem

Hi there! 

We use SoapUI 5.7.0 and we have a problem with a code grant authorization flow. Buildin browser shows "The page could not be loaded" everytime when we try to get the app authorization form (using authorization uri parameter). We noticed that soap ui makes three requests at once: first, just GET request from authorization uri without any parameters, and then twice GET with parameters. In our case the app returns a responce with http code 400 when we ask form without parameters and return 200 when with. Total: pushing GET ACCESS TOKEN call three requests and one of them wrong. Buildin browser show "The page could not be loaded" in this case. Is there anything we can do to fix this problem?

Thanks a lot.