Filters aren't working

[Hotelmariofan]

I am attempting to build a factory, and in doing that I need filters. The thing is, my filters will randomly stop working. I put them down, and yes they are the right way because they work sometimes. Just lately this has happened. I place them, set them to the right color, then put a timer next to them, instantly it may shoot one item through the pipe, but then that little red light on the filter doesn't go out, it just stays red, even as the timer keeps ticking. So when I break it, about 4 or 5 of the items it is taking out pop out, along with the other items going through the pipe, although they are not supposed to go there since they are color coded. Any idea why the filter gets full and accepts items but won't let you get them out until you break it? A glitch I'm assuming?