Can you snap a pic of it showing the habit of the canes and a close-up of the leaves?

Lots of folks here are very experienced and would be able to identify Ebb Tide foliage or canes versus rootstock foliage and canes.

The Neptune I planted this year had the same problem, but I was lucky enough to have about 3 canes of the grafted species to compare to the Dr. Huey canes that appeared suddenly from below the graft.

I would say the odds are not good, my own experience of both Ebb Tide and Midnight Blue is that they remain smaller compact plants.

Believe me, if you have rootstock coming up it is MUCH easier to replace the plant than to try to fight Dr. Huey for one or two canes of what you wanted. Been there, done that.

That's one of the overwhelming reasons to only buy own root roses. Another example is that in zone 5 where I once gardened there is no need to worry about winter loss of the rootstock. In those zone 5 days mail order own root nurseries were very difficult to find - I had to order from a Canadian company to get them then. These days they are abundant and many seem to be doing well as businesses as more and more people intelligently give up on grafted roses.

Own root roses do take a couple of years to establish, but unless you're 93 it's worth the wait as they outperform grafted plants ever after that. Hell if I were 93 I wouldn't likely be planting anything but I can hope I will still be doing so then. And even then I would plant own root.

I wish I could testify about Ebb Tide own root personally but it is one of only two roses I grow that are grafted. And only because I already knew I wanted it when I saw it in a local nursery 50% off. How could I resist? Well, I did try. I can tell you that like all grafteds I've grown, this Ebb Tide bush is UGLY compared to any and all of my own root bushes. The bush mind you. The flowers are fine.
But its ugliness dooms it to a future encounter with Mr. Shovel which I doubt I'd be planning to do if it were own root.

Although sometimes it is rewarding to recover a rose from rootstock takeover. Could think of it as an adventure! I've had a handful of roses on Dr. Huey with Dr. Huey takeover. As soon as those Dr. Huey shoots started growing, the grafted rose stopped. Quite completely. If you haven't already removed the rose, take a sharp knife (or saw), saw off all the canes below the graft, and make a few encouraging comments to the poor 1 Ebb Tide cane, and see what she does?

I was told my Cl. Aloha was toast, and about 1 month after her Dr. Huey surgery she exploded into the gorgeous fragrant climber I had originally purchased.

To be sure of no recurrence, you have to remove all traces of the rootstock shoot down to a slightly hollowed socket. If you leave a stump, it probably harbors latent growth buds that will grow out readily--whereas the old roots and neck below the graft are more reluctant to generate new growth buds. IMO, a plant can always be saved if there is life in the bud union (graft) or above.

My Ebb Tide is a standard. It grows very vigorously and blooms alot. I would guess yoours is rootstock taken over. Good luck with it.

I'm very curious to know how your Ebb Tide dilemma worked out.