Icy Terrain not processing after 1st hit or applying chill on multi-target (periodic bug)

poof00

When using icy terrain on more than one target it will periodically stop applying chill to one of the targets. Once this occurs with a new hit of the encounter it does not appear to correct itself -ie. the target cannot accept IcyT chill. With a single target, icy terrain will process 9 times. The combat log below is a two target icy terrain showing 9 ticks on one target (also will chill showing in the buff bar) and only one tick on the second target - with no chill being applied at all. MM shown to bracket the encounter only. This is across all build types of CW (MoF, SS, Rene, Opp)

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[Combat (Self)] Critical Hit! Your Magic Missile deals 7778 Arcane Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 4298 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 4492 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 4345 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 4521 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 4190 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 4847 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 5300 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 5230 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 5517 Cold Damage to Target Dummy.
[Combat (Self)] Critical Hit! Your Icy Terrain deals 6545 Cold Damage to Target Dummy.
[Combat (Self)] Your Magic Missile deals 4015 Arcane Damage to Target Dummy.
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