Answer: Based on your description, I am not sure what to suggest, especially since you are having such good experience with so many other roses.
This is a hybrid rugosa, quite winter hardy, and should repeat bloom during the season so I would expect a big flush in May to early June and then some repeating later in the season. Since it is a rugosa, pruning would be minimal especially on a new rose, and of course it would also be very sensitive to sprays so you would not want to routinely treat the foliage with anything as this would be likely to have an adverse effect.
Perhaps it was stressed last year due to the shipping and transplanting process and is taking its time to recover, or perhaps there is a hidden problem underground with the roots such as vole damage? If nothing seems amiss on careful inspection, perhaps you can locate a consulting rosarian through the local rose society who could take a look at it on site?
I'm sorry I can't be more specific. I am really hoping it will bloom well for you this season.
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