Since the last WordPress-update I noticed several times an unusual behaviour within the Wvr X-Plus Flex Columns.
Sometimes it isn’t possible to change the min.-width of desktop or tablet and it isn’t possible to write something into its CSS-Boxes.
This happens on different websites. It seems to be a bug. Maybe you can look for it.
(There is an inconvenient way to handle it: You have to keep pressing the left mouse-click until writing something. Then you can insert some text – very strange!)