I just received a follow-up from OOTP regarding this issue. The CSR stated that my e-mail client (Outlook for Mac 2011) is no longer officially supported (no surprise there). I stated that Rogers will need to update their FAQ regarding e-mail clients below, basically to only include anything newer than 2016?:
The CSR did state that he would contact the Rogers/Yahoo team once more to see if there's some sort of workaround that will work (like Yahoo has for their customers with older e-mail clients, discussed in one of my recent posts - link below).
I think I'll leave this for another week or so to see if they put a workaround in place. If not, I guess I'll have to upgrade to MS365, which is not cheap. I suppose I could also look at a different e-mail client, however, I have thousands of e-mails and calendar events in Outlook for several decades, so I would prefer not to.