Windows 10 upgrade --battery & charge state not displayed.

For some reason we have accidentally upgraded to W10 on the laptop this afternoon. By and large it seems to be working ok, but the one thing we have noticed is that the battery charge state icon etc is not now displayed in the tlower right task bar.

When I plug the charger in it does appear to be detected because I get the Acer battery/charger overlay displayed in the centre of the screen for a short period - just as it used to. I do not think this is a Windows function, more likely a an Acer function?

I went into Device Manager>Batteries and peformed a 'Scan for hardware changes' and the battery symbol then appeared in the lower right task bar as per usual. Plugging and unplugging the charger was shown in the icon so it appeared to be working and we were 'good to go'.

I then thought I had better perform a laptop restart to make sure it really was now working and stable. After restarting the icon did not reappear!

Tried the same trick in the device manager but no luck.

I have not performed any other software updates on the Acer.

I hope someone can help me get this rather vital icon to reappear permanently.