Is any one know how to fix it?

It happen only when 3 or more user working on the same form and one user updating a table. Very often it show updated records on the other user's grid. I make sure the key field use unique value with sys(2015) function. But it didn't work.

It not just happen on one form but many form using the same type of buffering as following.

Master table use table use Optimistic row buffering
Child table use Optimistic table buffering