Originally Posted by
xenologer
What looks like worn teeth is most likely profiling designed to assist in shifting.
you can either get a single-intended chainring who's teeth are designed to do the opposite -retain the chain.
or you can put the front derailer back on and lock it's limit screws so it acts as a chain guide.
+1. Even a singlespeed specific ring will not necessarily hold the chain in a 1x configuration if you are running a chain designed for shifting.