I created in 2 projects the same components: Back-end and Front-end.
And I filled for all tasks the component fields.
Then I created quick filters with the help of JQL: component in (back-end) and component in (front-end).
In one project these two filters work in another one of the filters does not work.
What can be a problem? I checked the misspellings and sure that there are no problems with that.