That’s odd but not completely out of left field, macros do experience some weird race conditions.
I ran into this all the time trying to use macros with fallthrough conditions like casting an instant and then something with a cast time. You can test it with something basic like:
/castsequence [@player] reset=7 Arcane Intellect, Conjure Refreshment
/cast Teleport: Dornogal
Spam that too much and you will be porting to Dorn even though that should be impossible. The more condition checks and lines between unwanted actions the more likely the game is to think that it should be looking farther down the macro.
But I’ve never seen it happen within a single castsequence line. I already use a macro like that for Alter Time and yep it does that for me too. How many PVP deaths did that cause. :<
/castsequence reset=5 Alter Time, Smite
also did not work, nor did sequencing AT and then another valid ability.
Makes me think that there’s something screwy with the way Alter Time changes SpellIDs, and the macro takes a second to catch up and realize it’s on the next entry. Since you can’t /cast spell IDs directly, you can’t even make it a strictly toggle-on button and have some other keybind return/cancel.