Hello.

I think we have recently stumbled upon an issue/bug from your end.
Our team is using the Upsert Records endpoint for Contacts in order to insert or update them. We are using a custom layout.
After we rename an already created field (Single line) of the layout we will be unable to update the value of it for every contact through the API call. We can only update it if we use the Old name (the one we had set before renaming it, which does not make sense)

For example if we created a field and called it "Field 1", in order to upsert it, our Contact data payload would include the line:

1. "Field_1" : "Some value"

This would work as expected. But after (manually) renaming it for example from "Field 1" to "Field 2", and the payload would include the line:

1. "Field_2" : "Some other value"
   

"Field 2" would not get updated.

The strange thing is that it would get updated only if we used "Field_1" even though we had it renamed.

As a result, due to some field renamings that we were doing on our accounts, we had problems that would cause data to either not get updated, or even worse get wrong values (This would happen if we "swapped" the names of 2 fields).

Thank you.