Odd red box showing at bottom of forms before being submitted

Try switching to the default theme.

I have this issue too. It seems that

div.wpcf7-response-output {display: inline-block;}

is overriding

.wpcf7-display-none {display: none;}

Sure, changing to the default theme solves the issue, but obviously that’s not a fix…

exactly what @curve said

Did anyone ever get a legitimate workaround for this??

Add this to your custom CSS in your theme… worked like a champ!

div.wpcf7-response-output{
display: none;
}