INVALID_FUNCTION error with GetRESTProxy in CXone Studio Snippet

I’m trying to call a CXone REST endpoint from a Studio Snippet but getting an INVALID_FUNCTION error. The documentation suggests GetRESTProxy is the correct method. Here is the snippet:

ASSIGN rest_proxy = GetRESTProxy("https://api.nice-in接触.com")

The script fails immediately at this line. Is the syntax incorrect or is there a specific configuration required in the Studio environment to enable REST calls from snippets? The error log just says the function is not recognized.