Autocomplete doesn’t work

Hi there.

It’s impossible to fill in any fields that have autocomplete in them – always reverts to an empty value no matter what you do.

Can’t replicate on the demo site, any ideas as to what might be causing this?

Tried uploading gif but wouldn’t animate, here’s a link instead:<br />
https://imgur.com/h4FZalG

Thanks for any help in advance.