Suggestions on Bing search broken

The endpoint "/AS/Suggestions" on bing.com expects the "cvid" parameter, currently being filtered out, yielding a 400 error if not present:

• With: https://www.bing.com/AS/Suggestions?pt=page.home&mkt=es-es&qry=nint&cp=4&cvid=48BCDF9F31014426B6405B8401331F06
• Without: https://www.bing.com/AS/Suggestions?pt=page.home&mkt=es-es&qry=nint&cp=4

Apparently the endpoint would work with the cvid being fake or static (ie "cvid=abcdef"), as long as it's present and not empty.