iMac won't upgrade.
I have an iMac 2017 iMac (Retina 5K, 27-inch, 2017) it will not upgrade to Monterey. Says I am up to date, which is Big Sur. On searching it indicates that my iMac can use Monterey, "iMac introduced in late 2015 or later" shown on Apple's service site. Why won't it update?
iMac 27″ 5K, macOS 11.6