Added screenshot to OP.
I did cast her skill on yellow reflecting monsters. The debuff already wear off by the time I noticed this bug and took the screenshot. You can see that my Onatel doesn’t even have any debuff on her. Connecting yellow tiles doesn’t gain her mana, and mana potion is disallowed, and Misandra skill doesn’t work on her either.
Thanks for suggesting to not bring yellow on this challenging event. I used her because she is the only decent mana control hero in my lineup.
P.S I just beat the final stage in legend with her. I consciously avoided using her skill on yellow reflecting monsters before I reached the final boss stage. I did use her skill against the final boss, the skill did get reflected but it didn’t bug this time. Maybe it has something to do with the number of reflects? There were only 1 yellow reflecting boss in the final stage, but I was casting her skill on 2 yellow reflecting monsters when it bugged.