调用eBay Merchandising SDK的getTopSellingProducts接口报错求助

我运行以下代码可正常获取响应：

from ebaysdk.merchandising import Connection as Merchandising
try:
    api = Merchandising(appid="YOUR_APPID", config_file=None)
    response = api.execute('getMostWatchedItems', {'maxResults': 10})
    print(response.dict())
    print(response.reply)
except ConnectionError as e:
    print(e)
    print(e.response.dict())

但将接口调用改为getTopSellingProducts后：

response = api.execute('getTopSellingProducts', {'maxResults': 10})

出现错误：

ebaysdk.exception.ConnectionError: 'getTopSellingProducts: Not Found'

我已确认密钥配置正确，且SDK文档显示该接口应被支持。作为API新手，我试过ChatGPT但未解决问题。

5月26日更新：
我尝试直接调用API，以下代码能正常响应：

url = "https://svcs.ebay.com/MerchandisingService?OPERATION-NAME=getMostWatchedItems&REST-PAYLOAD"
headers = {
'SERVICE-NAME':'MerchandisingService', 
"SERVICE-VERSION": "1.1.0",
"CONSUMER-ID": "<my APP ID>",
"RESPONSE-DATA-FORMAT":"XML",
"maxResults": "3"}

但将OPERATION-NAME替换为getTopSellingProducts后返回404。对比eBay官方提供的两个接口示例格式几乎一致，无法定位问题，请求帮助。

内容的提问来源于stack exchange，提问作者JohnRees77