I think the issue is not with saudi transit visa, it is with UAE visa on arrival. Unfortunately, Canadians have to apply for visa in advance due to the issue that happened early this year with regards to Emirates Airlines and Canadian Aviation Authorities. UAE immigration has become more stricter with Canadian passport holders and ensure that they secure a visa before arriving in UAE. Now, i would hope that your GCC visa would secure you entry permit, but again, this is all about UAE authorities. Try to arrange your visit visa for UAE in advance before you start off. Drive safe!