The project development was complicated and delayed (and finally stopped) due to the problems with engines. Typical for a number of other interesting Soviet designs in the 1930-1940s. Also, it didn't help that Myasishchev was ordered to lead the modernization of Pe-2 which in retrospect can be considered as a considerable waste of time and efforts since there was superior Tu-2 almost ready. Wisdom of hindsight...
Nice looking aircraft, by the way.