Stumped on a Cherry tree

Okay. It’s a sweet cherry mystery. We’re in Central PA. I have 3 sweet cherry trees. A Gold, a White Gold (I think), and one that has produced a very nice deep red almost black cherry a couple of years ago.
This year the Gold and White Gold have finished blossoming and started forming fruit.
The 3rd one has the slowest blossom-forming buds nature has ever seen.
Am I wrong to expect cherry trees to bloom at essentially the same time?
I’d suspect it might be having health problems but I think the buds are swelling.
You might be wondering what variety it is. So am I.
My experience with the purchases from the on-line nurseries were long ago, hit-and-miss, and riddled with lies & replacements so I lost track of what was planted.
QUESTION: any idea what’s going on with this tree?