Hi there! 
— Webflow engineer here.
We just shipped a temporary patch so that your grid layouts in the Designer shows up correctly as intended. Can you refresh the Designer and let me know if it fixed the issue? Also to provide a little bit of context surrounding this issue:
Our Grid implementation makes use of an API provided by the browsers that allow us to build this overlay, which shows any auto-generated columns and rows and allows you to adjust the values on Canvas.
The browsers implemented this API according to the CSS Spec as it was written at the time, BUT it turns out it actually wasn’t what the CSS Working Group had intended (they provide guidance in implementation), and as a such had to ship a fix to this “bug”, long after products like webflow.com and gridcritters.com have utilized this API. As a result, we no longer have a way to determine rows and columns that were auto-generated, which is why you see the bug in Chrome 81, and soon after in the other browsers.
Fortunately for us this does not affect live production websites and only occurs within the Designer. The caveat is that we had to change code to account for this limitation, which resulted in removing the auto-generated overlay UI to avoid breaking your layouts in the Designer. Going forward and until the browsers provide us with a way to determine how many columns and rows are auto-generated, please update the auto-generated values from the style panel.
Before
After
I hope this is clear. Please let me know what questions you have, and I’ll be happy to clarify.