Login to Joomla admin with one user
Go to the private message section.
Click on Filter Options
Hover on dropdown or click on the dropdown
The dropdown should have a placeholder and a collapsible arrow.
It's not easy to understand whether the filter option is a text input or dropdown. Also, there is no placeholder to the filter to identify what the dropdown consists of.
|Closed_Date||0000-00-00 00:00:00||⇒||2019-11-02 09:45:04|