Super weird that there's no seats whatsoever though. It feels more like a policy/decision than it does a matter of availability, otherwise you wouldn't expect to see any in the opposite direction (MEL-TPE).
I can't think of many routes offered that you wouldn't find at least economy availability within the next year.
Other weird ones is that TPE-SYD and TPE-BNE only ever have 1 seat visible in Prem Eco.
Wonder if they were a bit sick of QFF redemptions to/from TPE after opening up the entire network to QFF redemptions.
We flew redeemed quite often before this, and there was always tons of availability even at short notice.
Might see if I can snag a J+PE going through SYD/BNE and let the missus have the J.