Date dimension showing only 'UNKNOWN'

Dear All,

We have a cube, which gets processed once in a day. Recently we changed 'end date' in Date dimension to '2020/03/31' from '2015/03/31' and processed it. After process, Date dimension is not showing any dates except 'UNKNOWN'. 

I have troubleshooted by checking the view and the also did 'Explore data' in Data source view too and it is showing data and no change in the view in recent times.

Also tried by 'Process clear' and 'Process full' on date dimension, But no luck. Can someone shed some light into it.

Thanks a lot.

Regards Suneel