Strange issue with sort order

I've created a custom dropdown filters plugin to pass the data_search command to tablejx and stumbled upon a strange issue.

When I change the sort order for a column, then filter the results, and then sort the same column, I get the results back without filter.
Seems like the results are cached somewhere. Could you give me a hint where to look?

You can see it working at www.camerastuffreview.com/nl/inhoudsopga...lenzen-testoverzicht

Greets,
Ruben

That's it!

Thank you!!