Maybe I haven't looked into it enough, but the wiki says Macross Dynamite 7 takes place in 2046, or one year after the events in the original series. Personally, I feel like it happened around episode 40, given the atmosphere, and if you look at the cardboard Mylene cutout in episode 4 of Dynamite 7, you can see a date of 2-2-2045. Maybe they kept a cutout of her for over a year and just reused it.