Yep, I'm seeing the exact same problem here. Merchandising API , gMWI call. I'm using XML format, and you are using JSON, so that's not likely an issue. When I test/refresh this bug in my browser, I'm seeing approx. a 50% failure rate. This began @ Mon-20-Apr-2020 ~5pm US Pacific Time, +/- a few hours, based on my logs. I would guess that some eBay API servers are on the fritz. Some, but not all. I hope they fix it soon!