Unable to expand collapsed comments as anonymous user

Summary

Unable to expand collapsed comments as anonymous user

Environment

Not environment specific

Steps to Reproduce

1. add enough comments to trigger comment collapsing
2. Allow anonymous access to the project
3. navigate to an issue that has numerous comments and is collapsed and attempt to expand the comments.

Expected Results

Comments expand

Actual Results

Comments do not expand. Comment shows as 'loading' and never actually loads.

The below exception is thrown in the HAR file:

:path /browse/MODULES-1736?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&showAll=true&_=1445280562631

Fails with 404 error

Workaround

Turn off comment collapsing
Disable comment collapse