Grid Validation not providing old cell value

[James Zukowski]

We have a grid with a column defined as a VarDropBox. Each cell in the column has the 'Text$ defining the list of entries, and each cell can have a different list. The column also has a validation logic attached to the cells.
Processing through the panel will set up various fields and load existing data into the grid.
If I click from outside the grid into one of these cells and choose an entry different from the original value, the validator is provided a null value for the Old_Value$, which should actually contain the previous cell entry, from my understanding.
If I click into a different row in the same column, the Old_Value$ reflects the value from the previous cell, not the currently selected cell, as I believe it should.
Also, returning an error message does not restore the cell's contents to the previous value; it retains the (incorrect) updated selection.
Am I missing something?