Over the years I have had issues cooling with propane a few times. Problem has always been a dirty burner or dirty orifice. So when it's not working right. First thing I do is pull the burner an orifice. Start soaking the orifice in denatured alcohol, while its soaking use a wire brush and compressed air on the burner to clean it up..
On propane, I have never had any other issues.
Art & Joyce
35' DP Endeavor being pushed by a Kia Soul