Report for issues with no category for all projects
Because of the fact that the filter for categories is deleted when a report is saved as public and/or for all projects, it's not possible to create a filter for all projects that contains all issues that have no category.
Updated by John Molomby about 11 years ago
The same is true for "Target version". It's not possible to create a report for all projects that includes all issues with no version set. If an existing report is made available for all projects the "target version" filter is removed. As far as I know there is no legitimate reason for this.