Issues not showing up in backlog

[Oliver Gould]

I created several issues for my project, and I can find them in the search view, verify their project, status, etc., but they do not show up in the backlog for the given project. What I find additionally strange is that in the Project => Overview => Agile tab it shows 25 issues in progress, even though if I examine several issues individually they are all clearly marked as 'to-do'. Sorry if this is ambiguous, I'm not sure what else might be relevant to report here.

[Oliver Gould]

After checking various potential problems, I realized that the filter query for the board was returning an error. I simply created a new, exactly similar, filter query and switched the board over to the new filter, and voila.