Ritual bug: destructible objects count towards ritual

While running the "Sump" map I encountered a bug with the Ritual encounters where the ritual was still active when all the monsters were killed.
3 out of 3 rituals ended only when I destroyed a piece of... fence? Structure? I don't even know what it is, but I'm providing a screenshot what caused the bug:

Another example, I had to break a wooden fence to end the ritual: