Ok so quickly looked over https://chainheal.com/healing-skills-2-log-analysis/
Ascendance appears to be an issue. Spammed HW instead of CH while it was up.
Elemental Blast use seems a bit low to me, but she also wasn’t having any mana issues.
In fact mana seems like it was really high the whole fight (didn’t drop below 75% till the last 5s of the fight) … so not casting enough spells in general?