Not Displayed gantt Start date

[sh0716_lee]

Hello. In my Structure, Gannt start date column didn't display.

I have been used Gantt start date colunm.

Suddenly Gannt start date didn't display any data.

And It took long time to show other structure's data.

It feels like an infinite loop.

Are there any checks for this situation?
Please give me an advice.

Thanks in advance

[Veronica Johnston]

I also have the same problem, previous tasks display start and end date but any new task I add shows the dates as it is created, but after a refresh nothing

Screen shot before refresh

After refresh

But in the task the WBS gantt still has the date