It doesn't happen often but it happens when you start casting and instantly need to move. Then it either cancels or not
Also i do think that the cast time makes the global cooldown pretty akward but thats just me.
And you're right, Sch never had Lucid dreaming of any kind... It just makes less sense in the cross role than esuna for me, but both in there is not a good idea.
I'm too lazy to always switch around my cross role stuff so i always have Esuna anyways, considering people WILL eat status effects if there are any to eat.

They should just rework the cross role for healer/Tank because a lot of these skills are a MUST and not optional and then you have to make macros just to switch between all the useful skills.
And 1 button more will not lead to overkill button bloat.