Conflict between Membership 2 and GD Rating System plugin

This issue ( ) seemed to be back again on our site after we moved servers.
We initially thought this might be a conflict with W3 Total Cache since it was the one which was causing the issue previously but wasn't sure why it'd cause the issue again since the exceptions were still added to W3TC.
We repeatedly tried clearing cache but the problem didn't seem to end up in a solution until the GD Rating System plugin was suspected and deactivated. Then we purged the cache again and it seems the registration process is working fine now.
Any advice on resolving a conflict with the GD Rating System plugin? Any follow up on it would be helpful.