Filters won't apply to clips

[Hudson555x]

Sounds silly, and it’s a proven bug, click or double click on the check mark for the filter. I just duplicated what you have here also with 18.05.08, but I had to double click the check mark a few times to get it to do this.

Here is a link to a post explaining how it happens:

Selecting Video Filters

We do not do anything special in the list of filters for one specific filter (Brightness). You must double-click a filter name in the filter list to toggle it. You only need to single-click to select a filter or single-click the checkbox to toggle it. Now, I just found the bug you were having: any time after you have double-clicked a filter in the list to toggle it, single-clicking the checkbox does toggle the filter but not the checkbox itself!

Sometimes removing then reapplying the filter will make it work.