Using the following macro for a warlock:
#showtooltip
/castsequence reset=target/combat/10 Curse of Weakness, Bane of Agony, Corruption, Immolate
When I press the button I have this set to, it never moves past the Curse of Weakness cast.
If I move to this macro:
#showtooltip
/castsequence reset=target/combat/10 Bane of Agony, Corruption, Curse of Weakness, Immolate
Everything works exactly as normal. After some testing it appears that this only occurs when the Curse of Weakness is in the first slot. As as test, I put Immolate rank 2 in the first slot and everything works as expected. It appears this problem is a Curse of Weakness (non rank 1) problem. With rank 1 in the first slot everything appears to be working as expected.
This only appears to happen with Curse of Weakness as Rank 2 or higher. Corruption is Rank 1, Bane of Agony Rank 1, Immolate Rank 2