Gas fireplace partially lighting
I find the burner needs maintenance when not burning with all ports, usually the holes are plugged with rust and a wire brush works great to clean, in some cases with heavy cast burners I have needed to poke a steel wire through the holes to clear the debris out. Is there a safety issue? Yes you are not getting proper combustion this can lead to excess gas build up and even higher CO levels, usually burners are easy to clean give it a try with a wire brush and see if that solves the problem, if not a wire or small drill bit can be used to clear the holes.