Jira Software Issues disappeared when old Jira Work Management Project sent to trash

[Andy Ryan]

We had two Jira Work Management projects that were more than 2 years old and 2 years since there was any activity. One had no issues ever created in it. The other had only 1 issue. Both were created by users who were now deactivated as they are no longer with the company. I decided to trash them (rather than archive) because there was no value in them. When I did this, 200+ issues vanished from the backlog of an active Jira Software project's board. I checked the filter for that board and it does not reference Jira Work Management at all. I checked all the automation set up in all three projects and there is no reference between projects. I went over the field lists and same. All of the tickets in question were created within the last year, which was well after the last activity in the Jira Work Management projects. 

I can't see any reason at all that trashing those two unused Jira Work Management projects would cause issues in a Jira Software project to no longer display. There is no connection between that that I can find.

Has anyone else seen this?

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

Deleting a project (whether full delete or move to trash) only affects the issues in that project. 

I suspect the vanishing issues is probably a coincidence - someone else reconfigured something at roughly the same time you were trashing the projects.  The two cases where it would not be would be are

• if the boards now missing their issues were configured to include the dead projects - the trashing would break clauses in their filter. 
• There's an Automation or script that is changing issues when projects or other issues are changed.

But you have checked the filters and Automations, so unless there's another scripting app around, it won't be that (JMWE, Scriptrunner, etc)

I would start to investigate this by looking at the 200 missing issues - why are they missing?  Have they been completely deleted, or had their security levels changed?  If not deleted, why have they stopped meeting the Software board's filter?