"Incredible" is commonly used synonymously with "amazing". Even though this isn't literally unbelievable (the primary meaning of "incredible"), it certainly is amazing.
It's also relevant to note that "amazing to the point of not being believable" is only the primary literal definition, while you would have a legitimately hard time finding even a single colloquial use of the word that includes the "not being believable" part. A similar case is "awful", which nobody uses to mean "full of awe".
