When you call in to apply the cert make sure the agent waitlists you ONLY for the long segment. Do NOT waitlist the shorter segment.
Check DL.dum and look for "First available with Upgrade Certificate". If so then you can confirm both segments with your RUC when you call. If it says "First available with Global Upgrade Certificate" then you'll have to waitlist with a RUC.
Cross your fingers....it's looking like a very rough second half of '22 for upgrades on longer flights for PM's - even with those using RUCs.