"the words: service/services/goods to flagged words" The only one of those words had was "good" not "goods". I deleted it, and it still did not work. But, when I just deleted the whole message to the customer, then it finally worked. I have another paypal business account, and while this account has been having troubles, I've been using my other account to send the same invoices with the same messages without any problem. So, whether the problem is the flagged words or the messages area, it is only certain accounts. Thank you for sharing @devana I hope a real solution shows up, but in the meantime, this helps.
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