(Keita writing)

While Betsy was checking SDF status she found that some ASC signals were routed to ASC-DC5 only in YAW while output matrix elements for DC5 are all zero.

It seems to me that somebody used DC5 matrix elements to write down the previous SRC1 sensing matrix when they had to change it, knowing that DC5 is not used at LHO, and forgot to delete the "memo". Sensing matrix doesn't look like a good place to store this kind of stuff.