Having US operations most often does not create tax issues if you year a warehouse for shopping, especially not with any tax treaty.
What I have noticed on the other hand is that many US LLCs are set up from residents of countries with strict banking regulations (I think we recently discussed that Indian and Moroccan companies are not allowed to bank outside India without a special permission). And then due to the cheap costs, even more are set up for complete scams and other illegal objectives.
With the high number of abusive cases, it is no surprise that banks with reputation don't want to deal with it. There are still enough alternatives in Puerto Rico that charge for their administrative costs accordingly and are open to such businesses.
I personally feel sorry too for all honest business. But I totally understand the view of the banks. It would be nice of all of you if you could do honest business and abstain from selling fakes, luring people into scam subscriptions etc. This way, those who need it have access to banking for their business. It is always sad to see things go just because some have been abusing banking for what it was not meant for.