Filter only works for logged in users

It sounds like cache. Try to purge the WP Rocket cache and any cache tool you have.

Also try to disable WP Rocket to see if it is related.

Hello I have purged cache before without luck.

But WP-rocket has an option to test a page without applying its rules.
If you use the URL below it does work. the ?nowprocket is to dissable wp rocket.
https://langesoy.no/shop/?nowprocket

Do you know what configurations a chache tool needs to enable the filter to work?

Please check with WP Rocket’s team. With /?nowprocket on URL, product filter is working: https://share.zight.com/BlumeJnQ.

With WP Rocket, it has a script error: https://share.zight.com/Z4uEBJQv – probably due to script minify. See if you can disable Javascript minify or compile.