The Returns Portal requires a First Class or Priority mail selection as the default for customer initiated returns.
However, if First Class is selected, and the return item(s) weighs 16oz or more, the Customer will get an error that they have to contact the merchant to initiate the return. This is because Shipstation does not switch First Class to Priority Mail once it reaches 16oz, as is required by USPS.
Please Fix this!!! The workaround is to have all returns shipped Priority ($10 for a return! instead of $4.50), unless you don't mind you customers getting an error upon submitting their return, and then needing to contact you. Defeats the purpose of a Returns Portal