Ves and Gloriana spent too much time apart.
After Ves led Task Force Predator into the Nyxian Gap, his collaboration with Gloriana mostly happened through remote.
While that did not significantly impact the quality of their mech designs, they still grew rusty when it came to knowing each other's habits and preferences.
It also didn't help that both of them progressed their design philosophy significantly. Ves not only made several breakthroughs in his specialty, but he had also evolved his design style further.
The increasingly desperate circumstances of his task force forced him to develop new tricks and solutions to cope with the restrictions he faced. He put his life on the line for every change or modification he made to his mechs.