I completely disagree with most of what has been posted above. This forum is useless unless you at least tell us the State this is occurring in. The laws that apply and the correct answer to your question depends entirely on the jurisdiction you are in. Also in most cases the jury charge conference happens right before the case is submitted to the jury, in which case this trial has already occurred and there is really no reason the poster cannot talk about the facts of the case. Those facts are literally public record now.
I bet I could answer your question if I had some facts and I could read the indictments. Just based on these very limited details, it simply doesn't make sense and there has to be another explanation. It would be double jeopardy to charge someone with both felony murder and the underling predicate felony as well. Which makes me think that there was some nuance that actually separated the two charges, or perhaps you are confusing dismissing the predicate felony with simply omitting it as a lesser included offense in the jury charge. If either of these are true then it likely has zero effect on the State's ability to proceed on the felony murder charge. I would need to know alot more facts to be able to give a better answer.