FFX-2 HD Remaster - Via Infinito - Trema has been defeated, how do I go back through specfic floors?

Hey all,

Like my title reads, I'm playing Final Fantasy X-2 HD Remaster. I beat Paragon and Trema and now I'm looking to go back through specific floors of the Via Infinito in order to complete Shinra's Bestiary trophy. I've read some guides and GameFAQs docs and it seems like once you beat Trema, you're able to hit specific floors whenever you want (i.e Floor 20 - 40), but that doesn't seem to be the case in my game?

What's happening for me is I step into the glowing ring to enter the Via Infinito and my only choices are to start from Floor 0 or from the farthest I've gone, which is Floor ∞, where a Tonberry and Paragon wait for me to fight him again.

I'm know I'm likely missing something that's probably right in front of my face but is anyone able to shed any light on this?