Created a new page using a blank canvas. Added the Case model and only 2 fields. Field1 and Field2
Added a Field Editor to the page, deleted a column and then added a column set to the remaining column.
Added Field1 to the first column and Field2 to the second
Applied rendering to Column1 if Field2=Blank and applied rendering to column 2 if Field1=blank
No other formatting or rendering on the page
Preview and if I select the checkbox Field1 and immediately uncheck it, we see the same behavior as on my original page. Column 2 does not render. If I wait 2 seconds, it does.
Wondered why we did the columns in a column instead of columns in a field editor, so I tried the same test without adding the second column set and the same behavior. Check and uncheck quickly and the render does not happen.