What kind of hydrangea is it? What zone are you in? And a picture might help too.

Yes, show a photo of the blooms - maybe it is one of the "wild" ones with no florets - just true flowers that are tiny. If bees are attracted to it then it sounds like the flowers are providing nectar and pollen.

Some plants stay in the broccoli stage for a while (weeks). My LIttle Quickfire for example stayed like that about two weeks but is now blooming. The lacecaps, which grow more fertile flowers than mopheads, tend to wait more to open but they do eventually... unless there are squirrels or deer in the vicinity. My lacecaps blooms are now fading so have patience. it will be great if you can post pictures of what your new blooms look like too!!!.