Lost index files and ability to browse the save sets past a certain date

Hello.

We are using Networker 8.1 sp3

Last week we tried to perform a restore on one of our hosts and noticed we could no longer browse past the last two weeks. I verify the index files on the Admin console and noticed that all the indexes were wiped from a period of time as shown in the pic above. It looks like we lost the last 6 years of indexes. Can these be restored?

I tried to perform a scanner -I function to restore the indexes from tapes but it doesn't seem to do anything.