It is indeed an anytime FP, for certain listed attractions (copied/pasted below) - but the only Tier 1 listed is LWTL (and Soarin, but my plane lands at 5pm and it closes apparently at 5pm now, so my only Tier 1 option is LWTL which I wouldn't bother getting a FP for). (Maybe MS is Tier 1? IDK, we don't do that ride.)
And it states that it is NOT changeable: I cannot change it for TT. I can't change one of my other FP for TT (I guess b/c they are my Tier 2 FP, so not changeable to Tier 1).
I'm fine with Soarin shutting down early - that's life. But why not let my FP for it be used on all other Tier 1 attractions? I guess I could cancel all my FP and then choose TT if it becomes available, but I could lose Character Spot and I only have 3 hours in the park that night. (First world problems I know!)
From my email this morning canceling my FP:
Your FastPass+ selection for Soarin' from 6:00 PM to 7:00 PM on 06/16/2016 is no longer available.
As a replacement, you may now visit one (1) of the following FastPass+ experiences any time from 9:00 AM on 06/16/2016 through end of normal attraction operating hours.
Experiences
Soarin'
Spaceship Earth
Living with the Land
The Seas with Nemo & Friends
Disney & Pixar Short Film Festival
Journey Into Imagination With Figment
Mission: SPACE