I have this button I created in a sandbox:
/lightning/o/Correction__c/new?&defaultFieldValues= Audit_Finding__c={!URLENCODE(Audit_Finding__c.Id)}, Origination__c={!IF(TEXT(Audit_Finding__c.Scope__c) != "Corporate", TEXT(Audit_Finding__c.Origination__c), null)}, Origination_Entity__c={!IF(TEXT(Audit_Finding__c.Scope__c) != "Corporate", TEXT(Audit_Finding__c.Origination_Entity__c), null)}, Title__c={!Audit_Finding__c.Title__c}
This is working fine when i click my button i have the fields prefiled:
However I deployed in production my fields are not filled automatically. I checked the profiles rights on the fields I'm using in the URL and I have access to them (read and edit).
The button is the same, fields are the same (I checked them One by one). I just pushed again the layout aswell.
Here is what I have in production: 
What Am I missing? I notice a difference between the 'layout' of the pop-up but the object layout is the same :/
Also in my sandboxe the url i got after clicking is a modified url: https://XXXXSandboxe/lightning/o/Correction__c/new?count=2&backgroundContext=%2Fone%2Fone.app%23eyJjb21wb25lbnREZWYiOiJvbmU6YWxvaGFQYWdlIiwiYXR0cmlidXRlcyI6eyJhZGRyZXNzIjoiL3NlcnZsZXQvc2VydmxldC5JbnRlZ3JhdGlvbj9saWQ9MDBiN2EwMDAwMDNiTlZ0JmVpZD1hMTA3YTAwMDAwQkU0NktBQVQmaWM9MSZ3cmFwTWFzc0FjdGlvbj0xJmxpbmtUb2tlbj1WbXBGUFN4TmFrRjVUa013ZDA1cE1IZE5WbEY0VGtSdmVFMTZiM2ROUXpRMVRucE9ZU3h1VEhCU2QxWnRUR2xFV0UwMlVuY3hlRmRwWTB0bVoyZHZMVzU1WVd4TFJqY3hjMnA2YmtSdmFqQTBQU3haVjFwclRVZEthQSUzRCUzRCZ1c2UzMDdyZWRpcmVjdD10cnVlIiwicG9zdFBhcmFtZXRlcnMiOnsiaWRzIjpbXX19LCJzdGF0ZSI6e319.
In my production the URL doesn't seems to be interpretated correclty as the URL is not modified:
https://XXXXPROD/lightning/o/Correction__c/new?defaultFieldValues=Audit_Finding__c%3Da103V000000TEnO%2COrigination__c%3DManufacturing%20Site%2COrigination_Entity__c%3Dzzzzz%2CTitle__c%3DTraining%20-%20Local%20zzzz%20-%20Test&count=1
If any of you has an idea I feel very dumb to be stuck on that. Thanks.

defaultFieldValues= Audit_Finding__c)backgroundContextis just the lightning way of doing the ClassicretURLand was probably added by Lightning based on the way you were testing. In sandbox is this a copy-paste typo...?&defaultFieldValues=...? You have?&which is not correct. You are also URLENCODEing things that don't need it - like IDs, and those that do, like text fields