I tried out of the ZipRecruiter integration and posting jobs worked very well, but getting candidates back into Recruit didn't work as well. We found that the number of click throughs dropped dramatically due to candidates being brought to our website to complete our (very) short application and upload their resume.
Any chance you have set up the integration to include the 1 click Apply, similar to what we current have with Indeed? We currently use an XML file integration with Indeed that works very well. Candidates use the one click apply, and their resume is sent to Recruit and posted to the correct job and shows that it came in via Indeed.