Is there a lower chance of an upgrade when you're upgrading a single sector on a multi-sector flight?

Is there a lower chance of an upgrade when you're upgrading a single sector on a multi-sector flight?

I don't think I've ever had a successful upgrade when a flight had multiple sectors (e.g. VIE/LHR/SYD or IPH/SIN/SYD) marketed and operated by Qantas and another carrier (in this case, BA and MH, respectively). Whereas I've always been able to get upgrades where QF was the sole marketing/operating carrier.

Anyone else have similar experiences? I'm QF Plat by the way.

Are you talking about an operational upgrade or an upgrade award using QF points? If the latter your chances are zero as you can only use QF points to upgrade flights that are both marketed and operated by QF.

I'm talking about points upgrade, but only for the sector marketed and operated by QF. In the example above, for IPH/SIN/SYD, the upgrade request would be for SIN/SYD on QF. I can normally get upgrades if I travel IPH/SIN on day 1 and then SIN/SYD on day 2, but not if the entire itinerary was on the same day. I wonder if it's just a coincidence...