The PNW is noted for its humidity.....is it not and possibly the peony is receiving too much water.
The blackening of buds and leaves does suggest over-watering...and if rain is also added to the mix, then I suppose the buds, not producing well, will soon turn black.

Actually, to help the plant produce bigger, better bloom, it is suggested to remove buds that do not form well or do not open.
Where energy is saved to be put elsewhere, the plant benefits.

Hopefully the plant is planted at its desirable depth.
That too, while possibly not denying bloom, if it is planted slightly too deep, or possibly you have topdressed the plot, effectively putting the plant deeper, it might well produce a bud.....but a bud that doesn't proceed fully to opening.

Where freeze/thaw cycles do happen, it is suggested to mulch sufficient to defend against this.
The mulch would be removed in spring to allow the ground to thaw and dry naturally. Later on, the mulch can be put back to save temperature and moisture.

Just in case you might think ants have something to do with the buds not opening......that's a myth...the ants are there to dine on the nectar produced on the bud and do not have anything to do with the bud opening.