"Online checkout with Square: Invalid Square nonce" (WP and Gravity Forms)

[GLUFC]

I have a WordPress website with Gravity Forms and Square configured.  The Square payment works fine, but I have an option for offline payment or EFT and when this is selected, a submission fails and results in the error "Online checkout with Square: Invalid Square nonce".

I've tried disabling all plugins except the necessities for this form.  I've tried a different theme.  I've tried the form with AJAX enabled (and disabled).  I've tried disconnecting Square and reconnecting it, as well as switching between sandbox and live mode.  Nothing has helped.  
But, like I said, online payments using Square and a real credit card are working fine.

Please help!

[GLUFC · Accepted solution]

Oh man - how embarrassing. I found out how to fix it myself and will leave this post here for any future searches on the same error for people with a similar setup.

On the Square settings for the individual Gravity Form I had the issue with (NOT Square settings for Gravity Forms), where I had the Square feed set correctly.  I had to click on Edit and right down the bottom there was a Conditional option...  I had to enable this and set it for the condition that matched display of the Square credit card fields (ie. Online Payment Method).

[Laurie_]

Hey there @GLUFC,

Thanks for taking the time to share the solution here should other Sellers run into a similar issue! 🙏

Glad to hear you were able to resolve this on your side - don't hesitate to reach out to us in future with any other questions.