Mixitup filtering does not work anymore

Hello everyone,

I have used mixitup multifiltering with succes for a couple of weeks, but it stopped working. When i now use the filters it works for 1 second and the automatically resets the filters. I have changed nothing to my custom code before it stopped working and dont know whats wrong. can someone help me?
The filter is on this page: https://www.suforyou.nl/trips
There are 3 filters under the dropdowns: reisduur, trips and prijs.

Thank you,
Maurice