Summary

As per this article, the description of Hide completed issues older than function mentions that the function applies to issues in the 'Done' column, which should be the last column. However, when configuring a Kanban board and setting the option Hide completed issues older than in Board > Configure > General and filter, it also hides other issues in other columns besides the one in the 'Done' column. 

Cause

Cause #1

The column is configured to have a 'Done' status category.

Cause #2

The issues filtered in the column is in a status with no status category. For example, when checking the issue that is filtered, you notice that the issue below has a grayed out status.

When heading to Admin > Issues > Statuses, we can see that the status Waiting for Customer does not have a status category.

Solution

Resolution #1

Change the status category of the column.

Resolution #2

Add the status category for the affected statuses.

• Go to Statuses page by choosing Cog Icon  > Issues > Find  Statuses  under Issue Attributes category at the left.
• Search for the affected status and click on Edit.
• Choose a category that fits the status and click Update.
• Try to replicate the issue again.