Yes, he was in Europe at the time. Chernow's biography of Clemens, while ridiculously long (audiobook was > 40 hours) was also very good and spent quite a bit of time on this.

I do suspect financial losses were a big contributor -- but part of it wasn't just that he lost _his_ money, but also his wife's inheritance. Of course, even aside from this money-losing invention, they were quite the profligate spenders.