Filters not checked on result page

Dear OC-community,

I checked the forums but couldn't find a similar question.
I am using the standard opencart filters on my site (OC 3.0.2.0 running with a BurnEngine theme and among others the Complete SEO mod). The filters are working fine however on the result page the boxes are not checked. For example:

https://www.diestadtgaertner.de/gruener ... ?filter=28

Funny enough it's working on my DEV, see

https://dev.diestadtgaertner.de/gruener ... ?filter=28

I have no idea why this is. My best assumption is that it has something to do with redirection settings since on my live site I am forcing WWW whereas in my dev I do not. Does anyone have an idea how I could bugfix this? Where does OpenCart extract the filter from the URL when loading the site?

Any help would be much appreciated!

Thanks & best,
Torge

Hello! I have the same problem and I see that in your side is working now.
Can you please tell me what you did in order to fix this?

Thank you