Pull Mirror Failing

Summary

Pull mirroring has started to error

Steps to reproduce

If you visit https://gitlab.com/rawnet-deployment/hunters (private company repo) I see it has failed with a pull mirror error.

What is the current bug behavior?

Pull mirror is not working

What is the expected correct behavior?

Github updates should be pulled to gitlab

Relevant logs and/or screenshots

2:Fetching remote upstream failed: error: cannot lock ref 'refs/remotes/upstream/amend-url-field-members-area': unable to resolve reference 'refs/remotes/upstream/amend-url-field-members-area': reference broken
error: cannot lock ref 'refs/remotes/upstream/banner-picture-element': unable to resolve reference 'refs/remotes/upstream/banner-picture-element': reference broken
error: cannot lock ref 'refs/remotes/upstream/banner-text-size': unable to resolve reference 'refs/remotes/upstream/banner-text-size': reference broken
error: cannot lock ref 'refs/remotes/upstream/feature/folder-descriptions': unable to resolve reference 'refs/remotes/upstream/feature/folder-descriptions': reference broken
error: cannot lock ref 'refs/remotes/upstream/feature/tree-order': unable to resolve reference 'refs/remotes/upstream/feature/tree-order': reference broken
error: cannot lock ref 'refs/remotes/upstream/hot-fix/compose-message-scroll': unable to resolve reference 'refs/remotes/upstream/hot-fix/compose-message-scroll': reference broken
error: cannot lock ref 'refs/remotes/upstream/hp-banner': unable to resolve reference 'refs/remotes/upstream/hp-banner': reference broken
error: cannot lock ref 'refs/remotes/upstream/master': unable to resolve reference 'refs/remotes/upstream/master': reference broken
error: cannot lock ref 'refs/remotes/upstream/members-area-v2': unable to resolve reference 'refs/remotes/upstream/members-area-v2': reference broken
error: cannot lock ref 'refs/remotes/upstream/mullucks-master': unable to resolve reference 'refs/remotes/upstream/mullucks-master': reference broken
error: cannot lock ref 'refs/remotes/upstream/new-valuation-form': unable to resolve reference 'refs/remotes/upstream/new-valuation-form': reference broken
error: cannot lock ref 'refs/remotes/upstream/office-careers-tab': unable to resolve reference 'refs/remotes/upstream/office-careers-tab': reference broken
error: cannot lock ref 'refs/remotes/upstream/realcube-branch-fees': unable to resolve reference 'refs/remotes/upstream/realcube-branch-fees': reference broken
error: cannot lock ref 'refs/remotes/upstream/staging': unable to resolve reference 'refs/remotes/upstream/staging': reference broken
error: cannot lock ref 'refs/remotes/upstream/valuation-form-amends': unable to resolve reference 'refs/remotes/upstream/valuation-form-amends': reference broken

I've ran locally git remote prune origin which seems to have removed some of the above references but I'm not sure why gitlab fails?

Matthews-MBP:hunters matthewthomas$ git remote prune origin
Pruning origin
URL: git@github.com:rawnet/hunters.git
 * [pruned] origin/DO-NOT-MODIFY-pre-aws-members-area
 * [pruned] origin/alignment-issues
 * [pruned] origin/aws
 * [pruned] origin/branch-banner-opt-out
 * [pruned] origin/branch-notifications
 * [pruned] origin/bug-fix/members-area-notification-button
 * [pruned] origin/bug/null-property-value-search-results
 * [pruned] origin/bugfix/buyer-registration
 * [pruned] origin/change-office-emails
 * [pruned] origin/d9mimisE/generate-site-map-on-cache-flush
 * [pruned] origin/demo/members-area-react
 * [pruned] origin/encoded-slashes
 * [pruned] origin/f24
 * [pruned] origin/feature/adfenix-sma-tag
 * [pruned] origin/feature/message-compose-modal
 * [pruned] origin/feature/seperate-sitemap-cache
 * [pruned] origin/feature/stamp-duty-updates
 * [pruned] origin/fees-ui
 * [pruned] origin/fix-branch-tenant-fee
 * [pruned] origin/fixes
 * [pruned] origin/force24-aux3
 * [pruned] origin/full-width
 * [pruned] origin/google-docs-viewer
 * [pruned] origin/import-urls-from-csv
 * [pruned] origin/listings-ednpoint
 * [pruned] origin/members-area--ui
 * [pruned] origin/members-area-url
 * [pruned] origin/members-area/listing-height-fix
 * [pruned] origin/members-ui-check
 * [pruned] origin/national-campaign-banner
 * [pruned] origin/national-campaign-valuation-fix
 * [pruned] origin/new-homes
 * [pruned] origin/notifications-messages-ui
 * [pruned] origin/php-max-upload
 * [pruned] origin/print-js
 * [pruned] origin/promise-polyfill
 * [pruned] origin/recaptcha
 * [pruned] origin/remove-locrating-live
 * [pruned] origin/staging_pre_merge
 * [pruned] origin/update-realcube-endpoint
 * [pruned] origin/valuation-booking
 * [pruned] origin/valuation-branch-selection
 * [pruned] origin/valuation-cp-branch
 * [pruned] origin/virtual-tour
 * [pruned] origin/youtube-and-ui-fixes