"We can't display this page because your browser blocks cross-domain cookies" message for a specific record type

Hi All,

I am trying to edit a lead record type but I get the following message when I try to access it:

We can't display this page because your browser blocks cross-domain cookies, but you can view this page in Salesforce Classic. Click here to open this page in Salesforce Classic.

Please contact your Salesforce Administrator, it is possible that they simply need to allow the *.salesforce-setup.com domain, as described in Set Up and Maintain Your Salesforce Organization: Allow the Required Domains

The message ONLY appears for that specific record type, as I can access all the other lead record types we have.

I have already checked it with Salesforce Classic and the list of record types does not show that specific RT. Also, I have tried with incognito mode, with another browser (I use Chrome), I have added the URL to the "Allowed to use third-party cookies" list in Chrome's settings, I checked the SF help page 

https://help.salesforce.com/s/articleView?id=000391956&type=1

but I do not have the "DuckDuckGo" extension, so nothing works.

Also, the error only appears in our Sandbox (I can access in PROD and FULL sandbox).

Any ideas on how to fix it?

Thank you!