Is anyone else getting this upgrade issue lately as a Plat or Diamond? There is a weekend schedule change, and I take advantage of it to rebook to different flights in Delta Main that better suit my schedule. But then, after I find myself successfully rebooked in Delta Main, I am often unable to immediately get an upgrade to (wide open availability) Delta Comfort, or even to get on the list for a complimentary upgrade. This can be for some or all of the new flight segments. Have been able to resolve with agents but they seem clueless as to why. May be something to do with the new fare classes, but wondering if there is a fix or something I can immediately tell the agent. Thank you for any advice.