Screenshot (72).jpg

This is probably a really stupid question, but I can't for the life of me figure it out. I need to do some very basic filtering, but the dropdown box where you check off the things that you want to filter by is not defaulting to show checkboxes. This didn't seem like a big deal at first, but it's made it impossible to filter all but one things. For instance, to filter everything but values that are 0, I would have to manually click every single value in the dropdown box. Clicking "select all" is doing literally nothing. It's this way for all my excel documents. Does anyone know how to get the boxes back? I've included a screenshot of what comes up whenever I click on the manual filter button to show what is coming up.