Hi @scgame ,
We apologize for the inconvenience, as the sandbox currently does have some deficiencies.
We understand this is causing frustration and may be blocking you from testing. So we suggest using production to test if applicable. Please ensure you adhere to these [best practices|https://www.ebay.com/help/policies/listing-policies/test-listings-policy?id=5039] when testing in production.
Also for reference here https://ebaydts.com/eBayKBDetails?KBid=684 are the list of Unsupported Features for the Sandbox.You can use the getItemByLegacyId call. This method lets you use the legacy item IDs retrieve the details of a specific item, such as description, price, and other information the buyer needs to make a purchasing decision. It also returns the RESTful item ID.
The new APIs, such as the Browse API, don't normally recognize legacy item ID numbers.
initiateGuestCheckoutSession problem is now resolved please check and if issue still persist let us know.
eBay Developer Support
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