I would imagine that both stories have some element of truth in them. The European politicians could have used the story of the US calling in it's debts as an excuse for their failure to deal with the post war inflation, while the US politicians could blame the write-off of the debt for the same reasons.

There are two sides to every story, of course, and history is always subject to interpretation. In the US, Patton was a military genius who struggled against every other general on the Allied side in order to gain recognition and Montgomery was a posturing fool, while the British praise Montgomery for his remarkable achievements while denigrating Patton as a boor.

The truth is that both sides are partially right. Patton was a boor, but a great soldier. Montgomery was rather caught up in his own mystique, but was also a great soldier. They both were critical to the war effort. And both sides are probably partially right about the war debts.