mmm thats a tough one. as posted above always have a footbed in your boot. But I totally understand where your coming from, the intuition liners never hold ankles that well in my personal experience, but they are the warmest and most comfortable. I know they make a liner with a tongue and a bit more rigid backside of the liner (like a stiffer power wrap i think they call it) which may help. I dunno here's the link, https://intuitionliners.com/the-liners/pro-tour/
Also I personally feel the design of the FT isn't the best at holding your ankles down since the design of the boot is 3 piece. On top of that they use cables which makes the combination not too great, I feel my ankles not as supported in the boot just like you because of the middle cable. Try making the buckles a little tighter, that may help.
Especially that middle cable because that's the one that's gonna be holding your ankle down in the boot. Also try cranking that top buckle a little bit. I think my next boot is going to be a more free ride style boot like a nordica patron or something like that because that boot holds my ankles really well, but my bumble bees are so damn comfortable! lol
Scarpa liners is the same thing as intuition, not much help but here's a link. The problem is a lot of people are actually putting intuition liners and what not into they old or even new boots because they love the comfort and not many people are doing the opposite. Every boot comes with a liner but I hardly ever have people ask to get them a replacement liner. I hate to say it but you may want to look into a new boot or a different style boot. You can always make a boot bigger, tough to make one smaller. Here's Scarpa's link
Hope some other people have some more helpful input seeing as I didn't help that much but that's my 2 cents on the subject. Good Luck man, keep me posted I'm interested to see if there is a fix.