problem view "shaded with edges" if you click cancel in modrif

[areaimpianti]

I found a 3d display problem in "shaded with edges" mode (on autocad mechanical 2018 and 2019)
if you open a block with modrif (before), and you go back with cancel (_.undo) because maybe you opened the wrong block the display darkens (after). the only way I found to restore it is to reopen the same block and close it with the appropriate commands save changes or ignore changes.
but if you do not immediately notice the error and closes the design there is no more way to restore the display that remains dark.

Does anyone have a solution?

 

[lattu]

the modification of a block should always be closed with the appropriate command, you can also exit without saving