Hey John,
When we rolled out our new grids we had speed in mind. Unfortunately we had to give up the ability to drag column sizes. However, it is an option that we are looking to bring back.
The question I need to ask is; are you trying to drag the column size? or are you having problem in the wizard?
I have tested the wizard out on my side it and seems to work fine.
If you’re trying to drag the column size, try changing the size's this way.
1. Go to Customize
2. Edit your grid
3. in the wizard jump over to step 2
From this screen, you can set the size by pixel or by % of space
Hope this helps