Welcome. It sounds like some kind of caterpillar or army worm. (Or mean neighbor... ) Have you tried spraying the plant and the medium with an insecticide? Is there any other signs of a pest? I had a heck of a time figuring out what was getting my tomatoes that I was growing in a pot on my back porch. I found out after spraying and using seven-dust all around that it was a big water rat! It would come up and cut the tops off of my tomatoes. I finally caught him in a live trap that I borrowed from the university bio department and I took him to the Spadra Creek about 5 miles away from my house and let him go. Hopefully, he will never come back! hehe..
A few questions: Does this always happen in the same place? Have you tried elevating the plant or hanging it from above so that it is not sitting on the ground or table?
Glad you are here and hope you figure out what is cutting off your spikes.