Macbook is not locked when lid is closed and opened with iPad connected as a display.

I was having this exact same problem and it was really frustrating me. I actually don't understand how Apple, of all companies, could have this clear security breach on its most premium product, but I digress. The way to solve it is go to:

System Settings --> Lock Screen (on the left side bar) --> Click on the dropdown box for: Require password after screen saver begins or display is turned off. --> Select "Immediately"

Go to 'Security & Privacy' - and check the option - 'Require password immediately after sleep or screen saver begins'.

Even if you pull down the lid, it doesnt lock until the time provided in this field. SO make it immediately and it works. Just fixed on my mac.

naehva wrote:

I have a MacBook Air 15" and I use my iPad Pro 13" M1 as a second screen using Sidecar. Both are updated to their latest OS version (macOS Ventura 13.5.2 (22G91) & iPadOS 16.6.1(20G81)) but I noticed the following behavior on early versions as well.

When I close the MacBook, the screen turns off and my iPad disconnects as expected. But when I open it, my iPad reconnects and my MacBook turns back on unlocked and with all my apps open, just as it was before I closed it.

If my iPad is not connected or I lock the MacBook using the power button, it locks and I have to use Touch ID to unlock it.

I won't remember to click the power button or disconnect my iPad every time I close the lid and I do not want anyone to have free access to what is on my computer. I want my MacBook to lock when it is closed whether or not my iPad is connected. Is there a fix?

Thanks

Look at your settings and make some changes...(?)

ref:

Require a password after waking your Mac

Set sleep and wake settings for your Mac

I’m having this issue still. Happens on all my M processor MacBooks. My company provided laptop has the setting locked so it requires password after 5 seconds I think so I cannot select “immediately”.

I find that if I disconnect the power supply and external monitor and then sleep the MacBook via the menu or closing the lid; about 10-20% of the time when I open the lid again even 2 hours later; the Lock Screen isn’t shown and my laptop is not secured.

Something is broken, and it seems to always be when I unplug power or the monitor and then sleep. Once it has done it once then it’s ok. So now I have to sleep, wake, sleep; just to make sure it’s locked.

massive security issue. Company IT didn’t believe me until I handed them my MacBook and then they kept hold of it for 10 mins and then opened the screen to find it was not locked.

according to the battery screen it was asleep though.

I’m noticing it. I can replicate it more when I use the Apple menu to sleep the laptop and then close the lid before the keyboard backlight turns off. I don’t think that’s the only trigger for it because I’ve had it in other situations, but I seem to be able to reproduce it more if I do it this way.

This is happening all of a sudden to me, too. I've had MacBooks for years. This is the first time I've seen this (and my settings are all set properly). What's changed?