Unable to 'Attach Link' for post-submit redirect

I'm trying to redirect a contact form post-submit to another page on my website.
When I click on the 'Attach Link' to enter the URL nothing happens. No input field comes up for me to enter the URL.
I've scoured this forum and found no solution

I want to post-submit redirect from here -

To here - 

It sounds like you have an error, possibly in browser cache, you can clear that and see if it helps:

https://squarefortytwo.com/squarespace-guides/loading-editing-issues-on-squarespace-clear-browser-cache

Alternatively, contact Squarespace Support for direct support on your website:

https://support.squarespace.com/hc/en-us/requests/new#choose-topic

Thanks for your response, Ziggy.
That's a great article. I didn't know about the ability to save versions of my website, nor about squarespace cache. I'll find out how to implement versions.

Unfortunately clearing the browser (Opera) cache hasn't resolved the issue. When I click on 'Attach Link' I get this (nothing)

There is nothing in the forum or Help Guides about having versions of our site. All I see is duplicate sites, which we have to pay for. Any pointers gratefully received.

52 minutes ago, VPJ said:

There is nothing in the forum or Help Guides about having versions of our site. All I see is duplicate sites, which we have to pay for. Any pointers gratefully received.

There is no versioning available, my post was out of date.

19 hours ago, VPJ said:

Thanks for your response, Ziggy.
That's a great article. I didn't know about the ability to save versions of my website, nor about squarespace cache. I'll find out how to implement versions.

Unfortunately clearing the browser (Opera) cache hasn't resolved the issue. When I click on 'Attach Link' I get this (nothing)

I am also having this issue today with my client's contact forms. I have been emailing with a squarespace support member tonight. Hoping to figure this out asap! I will comment on this thread again when I hear back. Good luck!

Aubrey

2 hours ago, feelingantisocial said:

I am also having this issue today with my client's contact forms. I have been emailing with a squarespace support member tonight. Hoping to figure this out asap! I will comment on this thread again when I hear back. Good luck!

Aubrey

I'm at a dead-end on it, Aubrey. Will be great if you find the solution. And even greater if you can give me that solution 🙂
Thank you!

Same here- has anyone found a solution?

11 minutes ago, feelingantisocial said:

Received an email back from support early this morning!

Good to know, thanks for sharing!

47 minutes ago, feelingantisocial said:

Received an email back from support early this morning!

Many thanks, Aubrey.
I'll try a new contact form then.
Much appreciated
Vic

2 hours ago, feelingantisocial said:

Received an email back from support early this morning!

It works! 
Thanks 👍