I have seen the same problem in VFP ever since 5.0. It is very unpredictable and can occur also by sometimes clicking on the Scrollbar and quickly pulling it down with the mouse and then all of a sudden all of the records can disappear and the Scrollbar goes dead. I tried all sorts of solutions and the one the worked was to create a form off screen and Activate the form and then close the form and Setfocus back to the Grid. Fun Tricks! There are still little querks with the GRID control as of today.

For fun create a grid and use Row buffering and add some records to the Grid and then delete a record and refresh the grid. The record will not disappear off the Grid with SET DELETED ON. Then do the same thing with Table Buffers = 1.