Foliage looks a bit like Iceberg, including the lack of blackspot resistance.

Is Iceberg thornless? I thought it was pretty thorny, but HMF doesn’t indicate either way.

You got this rose from High Country. I'd suggest that you go to their web site, and look at the list of roses they carry. See what white roses that they offer are next to Polka in the alphabet, and you may solve your mystery.

Whether Iceberg is thornless or not depends upon where on the bush to climber continuum the plant exists. The original seedling was a bush with very few to no prickles. That plant mutates to a climbing sport which has large, sharp prickles, but that isn't an "on"-"off" mutation. It is a continuum so one plant may be short, bushy and smooth while the next is significantly larger with some prickles and the next may be quite large with many, large prickles and all of them are really shrubs, not mutated all the way to the full climber. Your rose COULD be Iceberg. High Country sells all three color and the climbing sport of Iceberg. Have you sent the photos to HC and asked their opinion on what it may be?

Thank you @roseseek, that makes a lot if sense. I will reach out to HCR and see whst they say.