Hope you are doing well. We found an issue when TWebDateTimePicker tries to convert and display float value into time format (HH:MM:SS). From below picture, you can see the warning message from development tool for detail and basically this leads that time can't be converted. As we have observed so far, this only occurs on Microsoft Edge under IOS system.
Yes, I did not change the decimal separator so by default it is period (.). Are you testing on IOS' edge or windows one? I have no problem on windows' edge.