Que'ing next spells now fails to cast

I'm trying to spam smite as my filler DPS spell. It's been fine since I started playing again until today. Previously, I could que up my next spell during the cast of the current spell and it would begin to cast:

A, A, A, A

Today i find that I have to wait a short period after a spell casts to begin the next spell, which hurts the DPS efficiency. When it fails to cast I hear a sound effect letting me know it didn't cast, but there is no messaging showing anywhere and I don't know whats wrong.

A, wait, A, wait

I haven't installed any new addons.
1.5 second global cooldown ?
https://www.wowhead.com/spell=71841/smite
You could do that in legion?
That was a luxury not extended to every class.

Smite is on a 1.5 GCD now
https://www.wowhead.com/spell=585/smite
Your haste will reduce the casting time but does not effect the gcd
I could spam the spell fine 2 days ago, so i'm thinking GCD is no the problem.
Also. It's only with Smite. It triggers a short cooldown after Smite casts, maybe a quarter to an eigth of a second.
11/09/2018 03:32 PMPosted by Durkon
Also. It's only with Smite. It triggers a short cooldown after Smite casts, maybe a quarter to an eigth of a second.
It's from a weird bug with wands, autoattack, and certain spells. (Smite being one of them.)

I've seem some people report that putting smite in a macro with /stopattack can mitigate the problem.