Timothy Luke has mentioned this so many times for a while now…
“The answer to your first question - castsequence is broken and has been since they took it out in legions beta and put it back at the last minute. It may or may not work for you. There is nothing GSE can do about it.”
This is just one reply from many of his saying so…
If you’d like I can hunt down all of them and post them where he’s saying it’s broken. And since I know a thing or two about macros I can confirm it is broken…