I have - sort of - a similar problem...although I could not find the exact problem listed, so this is the closest I've found. Here's the deal:

I have a customer that is located in another county. They purchased an item in my county, so I am NOT shipping to them. For some reason, the box for "I'm shipping to this customer" has been automatically checked in the Sales Tax calculation portion, making the tax incorrect. When I tried to uncheck that box and save, it just kept coming back checked every time. It seems like a glitch, but it is not happening on any other customer. This is also a customer that has several entries, so I cannot easily delete and re-create this customer.

I have been able to delete the customer address, but then i get an "Error" message that says that QBO was  unable to calculate the shipping location, and has based the tax on my store location (which is what I want) but why is QBO defaulting to "I'm shipping to this customer" being checked - and not letting me uncheck it!?