Hi there! ^-^
Heartseeker has a skill tree node, “Straight Through”, that causes it to trigger Puncture from dying enemies.
This effect seems to work fine, except when the enemy is frozen (and thus, shattered on death), which seems to prevent this effect from occuring (maybe because shattered enemies do not trigger most on-death effect, which this talent is considered to be?).
Here is a link to a quick video showing how the effect correctly works on non-frozen enemies, but seems to be prevented by freeze.
Side note: I wanted to provide a log file, but the link provided by the bug report template is broken: Log File. ^^
Take care!