Archives do not store Mastering Data. Or, rather, not trusted Mastering Data.
On KRCs, Mastering Data is stored in two parallel copies -- one on the hard drive, and one on the RRDC EEPROM in the base of the robot arm. During a controlled powerdown, using the batteries, the data on both ends is updated.
But when the batteries are dead, this update cannot take place. So when the robot boots back up, the two data do not match, and as a safety precaution, the KRC treats the Mastering Data it does have as unreliable. The only way to fix this is to re-Master the axes.
The way to prevent this is to ensure the batteries are in good condition. Normally, they need to be replaced every 3 years.
If your linear axis is made by KUKA, there should be an EMT gauge mounted to it somewhere, just like each axis of the robot. If it's a non-KUKA axis, then there should be a mastering pin, or mark, that you can use with the Dial Mastering menu option.
So we did remaster the Robot today and will proceed to do additional check.
I'm aware of the batteries in the cabinet used to allow for the system to be properly powerdown, not causing any data loss. But after the outage and after booting up the robot, there's no error message about the batteries low voltage so I'm quite unsure if it's just the outage that could cause the data loss, or whether it's also because of the batteries. That being said, We will replace the batteries soon, to prevent this happening in the future.