When accessing System > Issues > Statuses: all users are receiving a 500 error:

We are on a very old instance 6.3.4 but it has been stable until recently. I am at a loss what to check next, the only other 500 error support items I can find relate to different areas within JIRA such as workflows. Here are more details from the error:
Referer URL: https://---------------/secure/admin/ViewIssueTypes.jspa
com.google.template.soy.tofu.SoyTofuException: In template JIRA.Templates.Statuses.success: In 'foreach' command {foreach $status in $statuses}{call .statusRow}{param status: $status /}{/call}{/foreach}, the data reference does not resolve to a SoyListData.