Frost DK's Runic Empowerment passive was changed to 1.5% chance to restore a rune, however it won't sometimes.
Whenever your runic power is above 66.66 you should have a 100% chance to restore a rune when using frost strike, but it does not all the time, even using frost strike with 100 runic power won't restore a rune rather often. you can easily test this on a training dummy.
can someone confirm that this is not a problem on my side? i already handed in a bug report