I had the exact same bug a few months ago. The issue was that NetworkManager is supposed to work with systemd, but Ubuntu chose to implement its own replacement to systemd instead (libsystemd-daemon0 I think). The issue I had previously was caused by libsystemd-daemon0 not sending the "resume" event to NetworkManager. I'd bet this is tre same issue here...
I had the exact same bug a few months ago. The issue was that NetworkManager is supposed to work with systemd, but Ubuntu chose to implement its own replacement to systemd instead (libsystemd-daemon0 I think). The issue I had previously was caused by libsystemd-daemon0 not sending the "resume" event to NetworkManager. I'd bet this is tre same issue here...