I have an older PS4 console which I mainly use which includes psn plus. I have 2 of my kids sub accounts. I just bought a 2nd ps4. In order for both consoles to share games and psn plus I deactivated the main PS4 and on the 2nd ps4 I made it primary. So on my PS4 will it still auto save to the cloud? Or just the primary activated PS4?
I would guess that only the primary PS4 will auto upload, but to be honest the best thing you can do is to go on (Settings) > [Application Saved Data Management] > [Auto-Upload] on both PS4s and check the settings to understand how to make it behave properly