LTI plugin - has anyone ever got this to work?

I have been fighting with this for many hours now. I want to use the LTI plugin in the canvas LMS.

It seems that it will only work with 1.7, so I have a version of 1.7.16 running. I have everything setup as instructed, and in Canvas I can create the ELGG plugin, but when I try to use it it says that LTI authentication failed and to check the consumer key and secret, which I have done many times. I do not know what to do next.