Infusing whipping cream

It makes a difference if there are traces of fat/oil on your bowl or beaters. The fat that is within the cream is a whole different story. Try whipping cream with grease on your beaters and you'll see.

I think it is because you heated the cream to boiling. That would have changed the cream. Perhaps just heat the cream to warm rather than boil it. It may have done something to the bonds of the fat with the water in the cream to boil it. I don't think it would matter if there was any residual oil on the beaters since cream has a high fat content so that wouldn't effect the cream chemically the same way it ruins egg whites.

I wonder if the cream was not as chilled as you had hoped. When I infuse cream, I put the ingredient in the cream and let it sit overnight in the refrigerator.

p.s. And absolutely no trace of grease or oil on the bowl or beaters. But I suspect you knew that already!

I usually find it's because the cream, bowl or beaters weren’t cold enough. What’s worked for me using lavender is to steep the blossoms in the cream, strain cream to discard the flower bits. Put cream in fridge until very cold. Put beaters and mixing bowl (if you’re using a different bowl to beat) in the freezer until very cold.

If you’re adding a little sugar to your whipped cream, another method is to let the elderflower or whatever flower or herb you're using sit in a jar of sugar for a few days, and then just use the scented sugar in the whipping cream.

Another approach might be to create an elderflower infused simple syrup. Then whip your cream until it is almost at the stage you want it and add 1-2 tablespoons of your elderflower syrup and keep whipping until it achieves the stiffness you desired.