Lock screen doesn't appear when resuming from suspend

Do you mean when waking up from "suspend"? I'm facing the same issue when waking up from suspend. Can you make sure by going into the suspend mode manually by clicking on it and then waking up?

Thanks.

Yes, that's what I mean. It happens when I suspend manualluy too.

I can confirm this too.

Additional information. Same issue when running sudo pm-suspend.

Also, screensaver is set to blank screen and lock screen. But also fails to lock screen when it activates.

ctrl-alt-L will correctly lock screen.

When I suspend by closing the lid and then open, I can see my desktop for 2-3 seconds before password dialog shows up. I wanted to file that bug (and I will) when I found this one. So I tried manual suspend and I can also see I don't get password prompt when I un-suspend after manual suspend.
18.04

I can reproduce this all the time on Ubuntu MATE 18.10.

I can also confirm this for my installation of Ubuntu MATE 18.10.

I can confirm that suspend locks on resume when closing lid. It does not lock when suspended from menu on 19.10 20190908

On 18.04.03

If suspend is called via `systemctl suspend` lock does not occur when resumed.
If suspend done from Power panel applet indicator screen does not lock.
If suspend done from Menu screen is locked.
If suspend is done via closing laptop lid screen is locked.

On 19.04

If suspend is called via `systemctl suspend` lock does not occur when resumed.
If suspend done from Power panel applet indicator screen does not lock.
If suspend done from Menu screen is locked.
If suspend is done via closing laptop lid screen is locked.

On 19.10

If suspend is called via `systemctl suspend` lock does not occur when resumed.
If suspend done from Power panel applet indicator screen does not lock.
If suspend done from Menu screen is locked.
If suspend is done via closing laptop lid screen is locked.

Please ignore my comment #8, now hidden. I was incorrect in my terminology re "menu". I'm also finding what has been posted in comment #10 for the 19.10 release.

On 19.10 current

If suspend is called via `systemctl suspend` lock does not occur when resumed.
If suspend done from Power panel applet indicator screen does not lock.
If suspend done from Menu screen is locked.
If suspend is done via closing laptop lid screen is locked.

On 20.04 current

If suspend is called via `systemctl suspend` lock does not occur when resumed.
If suspend done from Power panel applet indicator screen does not lock.
If suspend done from Menu screen is locked.
If suspend is done via closing laptop lid screen is locked.

Upstream bug reports:
https://github.com/mate-desktop/mate-screensaver/issues/228
https://github.com/mate-desktop/mate-screensaver/issues/84

Seems to be an issue with mate-screensaver not supporting the PrepareForSleep systemd signal (it was previously supported but it was not configurable, so they removed the support).

As mentioned in one of the bug reports, a workaround is to install xss-lock and then create an item in the Preferences' Startup Applications to use:

xss-lock -l -- mate-screensaver-command -l

The xss-lock application will detect the systemd signal and instruct mate-screensaver to lock the screen. You can create the startup item manually or you can create a .desktop file in /etc/xdg/autostart/ to enable it for all users.

This is really a kludge, but it works.

Status changed to 'Confirmed' because the bug affects multiple users.