Rope Dart +9 did not grant a guaranteed extra turn

Platform: PC, Steam client
OS: Windows 7
Game speed: x3
Game mode: Boss Raid (Level 325?)

Fully upgraded Rope Dart (+9) did not grant me an extra turn. There was no frozen effect active.
I used it on an Orc, but somehow it was ignored. This screenshot was taken 1 or 2 turns after.
The issue is hard to predict and it happens on random occasions and quite rarely, but it’s there.


This issue reminds me of a Skeleton Key +9. Same issue.