I don't know if it's a glitch of visual bug. But Violet's training bar doesn't go up. I have 125.85 points on it, and it is still 5% charged. It might be because I got it to 100 points before doing Lenya's quest line or something but idk what to do.
Violet's progress should go to around 150 if you keep training her and progress to the next part.
And doing Lenya's story line shouldn't affect it. You'll actually need to do both Lenya's and Jasmine's storylines before Violet's at some point, to progress Violets.
If you can't progress Violet's story, try making a new game, jump to act 2 and see if you can do it.