Blight monsters spawning inside an orichalcum ore can't be damaged

Hello!

Just as the title says, I have a Blight spawn portal just inside a Settlers orichalcum ore, and it looks like monsters spawning in this can't be damaged at all, so I can't complete my blight. I don't know if it's relevant but it happened in Phrecia softcore.

Bug Report ID: #2078557583

And here's a screenshot :

Thanks for reading and have a good day!