Stuck on Checking CI Status

I created a Jenkins CI service (not the deprecated Jenkins CI service). It seems to be working. Jenkins is performing the build. However, in Gitlab, the merge status is stuck on Checking CI...

Chrome Developer tool is returning: {"title":"added readme","sha":"6f957963","status":null,"coverage":null}

What am I missing? Our Gitlab version is GitLab Enterprise Edition 8.11.5-ee b7548a49