Hey thanks for playing!
By design the key of playing Daybreak against Cadence is to find openings and try to stagger as much as possible to interfere with the Appeal build-up (Subdue is a very useful card, despite having 1 windup). Cadence's defense is very weak so basically if you land every Ruthless Strike you would win. But the intention is that once you get familiar with the mechanics and all the other characters (I'm planning to add more characters in the future) you wouldn't use Daybreak again. He's not meant to be weak, but he's meant to be a tutorial character that is very basic.
Could you elaborate on the bug a little bit? Was the timeline indicator consistently wrong during that round? It could be an async issue.