Shatter Glacial Castsequence Working off and on

Ok ladies and gents, I am trying to figure out why this sequence works sometimes and locks up after glacial spike other times. The point is to shatter glacials spikes and this sequence will work for a bit and then stops casting anything after the glacial spike. It will cast the glacial spike and not the rest of the line. In the macro I use, I have everything with a nomod conditional so when I use the ctrl mod conditional, it will only fire that line. I’ve tried the line in all locations, premacro, keypress, keyrelease, sequence and even priority, sequential or whatever whenever available. As I mentioned it will work without an issue for some test runs, then others it will flow the line a few times then lock up the castsequence after the glacial spike and not cast flurry nor ice lance. Also it doesn’t lock up the macro itself. If I release my conditional, the macro continues on with frostbolt, frozen orb and so forth, I get another brain freeze proc with five icicles and it will cast the glacial spike again but not do the rest. I’ve also tried just glacial spike with flurry, and glacial spike with ice lance. Both variants gave the same results. I even tried doing /cast [mod:SHIFT] Glacial Spike and /castsequence [mod:SHIFT] Flurry, Ice Lance in two seperate lines. I feel like its something to do with GSE or the way I have the line set up based on the fact that the line does work every now and then. Some insight would be appreciated as I am curious as to what is causing said lockup every now and then.

/castsequence [mod:SHIFT] Glacial Spike, Flurry, Ice Lance