Advanced filtering not filtering out certain words

Howdy,

I'm having some issues with filtering out values that contain either the word "DRUM" or "IBC" when using the advanced filtering option.

As you can see here here I entered "does not contain DRUM or does not contain IBC" but as you can see these values still show up. When I use "contains" it works and only shows the items that contain "DRUM" or "IBC" but it does not seem to work the other way around.

I have no idea why this is the case.

Any help would be much appreciated!

Thanks!

Niel