Hi,
Thank you for that.
Okay, I checked your configuration, and the issue is a bit more complicated than that. I did not know this is actually a multisite installation, and you have lot of sites selected as the source. There are also some categories excluded under the Advanced Options -> Exclude results panel.
I believe the cause of the problem are these excluded categories, for some reason those conflict with the filter. I am not sure which one it is, but when I removed them, it started showing results. I guess there is either an ID conflict, or something I am not aware of yet.
Generally, it is not a good idea to use exclusions/filters when searching multiple multisie blog contents, as those categories does not exist on different sites, and may lead to conflicts.
I have found a possible working configuration:
– Try changing the Frontend search settings -> Andvanced like this: https://i.imgur.com/m7EPyhX.png
– And remove the exclusions, as probably one of them has a false effect: https://i.imgur.com/WX4HMzU.png
Now this configuration will have the filter active, only when at lease one item is selected, probably giving the best possible results.