My iMac (Retina 5K, 27-inch, 2017) won't update

Karen Sue wrote:

My iMac (Retina 5K, 27-inch, 2017) wil not download Monterey OS, even though it is listed as compatible. Could it possibly be a setting I forgot about? I have the computer set to automatically update. I am runing Big Sur.

Yes the computer is listed as Qualifying for macOS 12 Monterey

Use this Terminal command to only List all versions of macOS this computer Qualifies to run

 softwareupdate --list-full-installers

Does the Monterey 12.7.5 appear and is listed ?

If Yes, use the Terminal command

Suggest copy and past into Terminal and hit the Return key

softwareupdate --fetch-full-installer --full-installer-version 12.7.5

It will attempt to download the Full ( 12.xx ) Version of Monterey

If successful a new application called " Install Monterey Application " will appearing the Applications folder

Stop there and Always make a Time Machine Backup  before doing any upDates / upGrades 

When ready, launch the installer and follow the prompts

softwareupdate --fetch-full-installer --full-installer-version 12.7.5

Have you tried to download it directly from the App Store : App - Store - macOS Monterey?

Are you running any VPN, Anti-Virus, or Cleaning apps?