I had such trouble with my guy with this problem. What finally worked for us it to feed them in the dark, after I've noticed he is sleeping in his floating wisteria. I also cut down on the population of other fish so I can feed less. And if he wakes, I trick him to stay in his wisteria by dropping him a few of his pellets, which he vastly prefers, in the corner of his plants, so he takes some time to get to them.
My bettas: D'Argo + the girls Jullanar, Lalla, Razz, Rayleigh, Aviendha, Arya, & Lovelylocks
plus the other guys Toni, Eli, and Clinton (platy, guppy, and molly) a kuhli- Burt, 2 yoyos- Duncan and Ma, and otos, Laurel, Hardy, Larry, Curly, and Moe, plus the kitty, Clara the Impossible Girl.
SIP: Turk (teal VT), Azul (royal blue VT), Jerrica Benton (pink cambo CT), Lady Amalthea (blue cambo CT), and Jadzia Dax (blue VT)