Weird Issue on Click

Hi, working on a staging site and I have seen an issue where clicking on the dropdown isn’t working and the user needs to click and hold for the dropdown to remain open.

You can see this at http://tsg-com.flexxstaging.com/ and the white filters/dropdowns at the top.

I cannot replicate this but it happens intermittently on PC/Chrome. The users Chrome appears to be up to date.

Has anybody else seen this? Is it working as expected for you?