The web dashboard still shows that the miners are inactive: everything is showing zeroes, even after I refresh the screen.
Tried full reboot? Dashboard can be dodgy at times. Reboot is often easier than manually digging for services to restart, because obviously it restarts everything.

I bet you changed the time zone on the OS.
Same thing happened to me yesterday. Miner kept running fine according to slushpool, but all stats were empty.
Preformed a system reboot and everything has been problem free since then.