Speaking from first-hand knowledge, and maybe RA86 can confirm this, but the upgrade is only confirmed if there is a seat in F available. If there are no seats in F, then you are added to a waitlist. However, this waitlist is manually (or automatically after certain human review of the load factor of the flight) processed. In short, if seats are dumped to F during EUA, unless you catch this and call in to claim your seat, it will be awarded to Elites above you, regardless of your status. However, presumably, your elite status would get the upgrade for free, and hence you would not want to use a cert in order to upgrade.

In short, although your flights might be WL'd, don't hold your breath, and definitely do not assume the process is automatic.

Be diligent, and the seat is yours.