I can see a situation of war breaking out between Germany and the USSR and that could be over Poland and it could go something like this.

Germany (Hitler) agrees to cool it over that Polish Corridor but gets Poland to agree to hand back Danzig and Germany also agrees to a Mutual Assistance Treaty with Poland. While Poland staving of what they perceive to be an eventual threat by Germany signs Mutual Treaties with both Franch and Britain.

Poland hands back Danzig and as a reward Germany agrees to some obsolete weaponary to be shipped to Poland, and as this goes ahead Poland also signs on more vital Mutual Assistance Treaty this time with Italy. And so Soviet designs on Poland have been curtailed.

Now we come to The Soviets conflict with Finland, with the eventually the USSR being kicked out of the League of Nations. The Winter War does not go well for the Soviets but sheer numbers of troops effect a victory.

I'll add more later