Closing Gus work item does not close Git Issue

Steps to reproduce:
1. Create a Git Issue
1. Link it to a new Gus work item
1. Mark the Gus work item Fixed, then Closed to emulate typical Gus workflow

Expected results:
Git Issue is also closed when the Gus work item is closed.

Actual results:
Git Issue is unaffected.

Real world example of Git Issue and Gus work item (notice I had to manually close the Git Issues July 3rd even though the Gus work item was Fixed/Closed days before):
https://github.com/salesforce/lds/issues/632
https://gus.lightning.force.com/lightning/r/ADM_Work__c/a07B0000006th1tIAA/view