We planned a trip to Canada (YYC) from Mexico (MEX). We have valid Mexico passports and received our eTAs well in advance. At the airport, we were denied boarding and the only explanation was advice to contact the Canadian embassy. The Canadian embassy contact we have is only for Canadians. While we continue pursuing this avenue, we are wondering if anyone else has figured out how to determine why boarding is denied when we, apparently, have everything in order. Thanks in advance.