Usung uBlock Origin firefox extension blocks parts of site

If using marktplaats.nl ore www.2dehands.be, as soon as uBlock Origin is activated, you can’t search anymore for items on those sites.
After disabling uBlock Origin the sites work fine.

I hope this is the right place to describe this issue

This is GitHub community,
But anyway you can still whitelist those sites in uBlock Origin.

uBlock Origin has a logger that lets you see what gets blocked and why:

Once you know that, you could decide if you want to write exception rules, or possibly report the issue to the authors of the relevant filter list. Or maybe do nothing, if the blocked request seems like a questionable site.