Possible bug - Check in/out filter options (reservations page)

Hi
Our hotel staff have shown me a problem with the filter options, specifically the fields:

Check in from

Check in to

Check out from

Check out to

Once a filter has been searched for, the 'Clear' button is greyed out and cannot clear. However, if you type anything into one of the normal text filter fields and press enter, the clear button shows correctly. Other non-date fields appear to be correct.

I've just tried it with my experience reservations, and the same problem occurs.