For this problem you have to deselect "Shift+Cursor always char select" in:
Tools > Options > Editing > Selections.
In CUA emulation:
Hold down Shift and then press Cursor Left followed by Cursor Up.
Expected result: You should get a 2x1 block.
Actual result: You get a 2x2 block.
The block is extended to the right to include an extra column.
I think this is a regression problem in V20.
I think it is OK in V19.