Squash feature fails when using a Push Rule

Summary

We just started to use the new Push Rules feature in GitLab EE on prem. Starting with something small, we are just requiring an issue # be input when committing code into our projects. However, when trying to do a merge request and doing the "Squash" feature, it errors out "Something went wrong during merge pre-receive hook".

Steps to reproduce

Added in a push rules into a project such as this one:

(?i)issue #([0-9]+)

What is the current bug behavior?

The error prevents the merge request to be merged and refreshes the page. Even trying to modify the merge commit message doesn't fix the issue.

What is the expected correct behavior?

To squash and merge the request

Results of GitLab environment info

We run the on prem version, but am not able to see that information

Possible fixes

I'm assuming that under the hood it is failing because it is trying to meet that push rule requirement, but isn't something shown or allowed to be edited, so it just fails.