Cannot refresh AWS Web console during EC2 reboot

Question

We were relying on monitoring (and refreshing) AWS Web console to see the current state of EC2 instance and every time we issue 'reboot' of EC2 instance, we could clearly see color change for 'Instance state' from Green to Yellow and other changes visually.

Started recently, when we hit reboot - there is no visual change in Web console (even after refresh every 5sec) and 'Instance state' is constantly green, 'Status Checks' does not get changed at all (stays 2 out of 2 passed).
That led us to investigate reboot command and spend hours in troubleshooting.

It seems that problem is only visual and that EC2 instance actually gets rebooted.
Why AWS Web console does not get refreshed properly anymore?
And what is the method to rely on to see current EC2 state? (Up and running or Down etc.)