@Ebubekir_Tabak ,
Good Day!
Welcome to the community!
Ideally, it will work, Have you gotten the response with the data which you sent?
if you get the response then, kindly reload the page to check if it is reflected in the custom_field.
@Ebubekir_Tabak ,
Good Day!
Kindly create the L2 support ticket for the same,
the CURL which you shared seems to be good and I am assuming there might be some issues with the product.