For anyone who may be looking for what was changed to fix the issue by Dan-From-Ryviu. Here it is:
The issue, at least what I found on my end, was the selector .header__icon .icon-close.
Double check to see what the actual element is responsible for closing the mobile menu. For my Dawn theme it was .header__icon–menu listed as the correct selector. You can locate it in the inspect element.
I put this code on my theme.liquid file but its not working on my dawn theme. Can you please check here is the link of my website https://drinktwodrums.com/@VRAGO