Perplexity rune with thieves is glitched.
Did you actually interrupt anyone with your daze? Because it only is an interrupt when the other player is casting something at the same time and you interrupt that cast with your daze… It also shows “Interrupt!” above the enemey player.
https://wiki.guildwars2.com/wiki/Interrupt
I use this rune myslef in combination with skills that daze, and never had any problems with interrupts caused by daze and the confusion procs. The rune has some other bugs where you eat your own confusion when you get interrupted by basilisk venom, but that’s a different story.