Thanks for the reply void. Somehow it is back to normal now.
It was an internal drive, not unplugged or disconnected. I don't know what happened. Maybe a restart from sleep fixed the issue? Im also running bitlocker on the drive btw.
Anyway, good to know why it was dimmed. I guess somehow the drive was registered as disconnected.
Enabling debug logging before the issue occurs would confirm the issue.
It depends on the drive, volume and error returned from the system.
Everything sees NTFS volumes as offline if Everything is unable to open this volume and read the USN Journal.
In this case, it's most likely the drive was bitlocker-locked so Everything was unable to read the USN Journal.
Everything sees folder indexes as offline if the Windows ReadDirectoryChanges API fails.