Custom fields don't retain value Follow

 I'm new to YouTrack in the cloud. 

I've created system wide custom field ("Estimated time (days)" as float). It appears on the issue form. Clicking on the input area turns the default value label ("No Estimated time (days)" to  a text box. I can type a float in the text box but once I click out the value "No Estimated time (days)" replaces my float.

Please help.