What the docs say:
Official docs (MicrosoftDocs bing-docs, query parameters reference): the market parameter gotchas. mkt is language-country like en-US. mkt and cc are mutually exclusive, do not send both. To see which market Bing actually used for a request, inspect the BingAPIs-Market response header. Keep offset below totalEstimatedMatches minus count, otherwise you page past the end.

What works:
When calling Bing Web Search: pass mkt as language-country (en-US), never together with cc, they are mutually exclusive. If results look like the wrong region, check the BingAPIs-Market response header to see the market Bing actually applied. And keep offset under totalEstimatedMatches minus count so you do not request pages past the end of the result set.