The Nobel Peace Committee does not generally award Peace Awards during periods of widespread war barring exceptional circumstances. For example, during World War 1, the Committee gave no awards from 1914 to 1918, except for the 1917 award to the Red Cross. Sometimes the Committee defers a decision to ensure that the winner’s legacy and efforts were genuine. The Committee awarded no Nobel Peace Prize in the year 1919 itself. The Committee awarded Wilson's 1919 prize a year later, simultaneously with the 1920 award, both for contributions towards the League of Nations. This was largely due to political considerations. Opinions of Wilson in 1919 were very poor, but by 1920, they had warmed. So in 1919 it would appear as if there was no award, but on lists of awards it shows up since it was awarded retroactively.

A combination of the above two factors, war and delay, would contribute towards the Committee awarding no prize in 1923 and 1924. From 1923 through 1926, the Committee awarded no Peace Prize due to the persistent feeling of conflict in Europe. For a while, it appeared as if violence and conflict of some kind could break out again between France and Germany, and that people were not working towards a lasting peace, only a “Victor’s peace.” During this time, the German people were passively resisting repayments, France still occupied the Rhineland, and the United States had pulled out of the treaty of Versailles and refused to join the League of Nations. Eventually, by 1926 it appeared if things were heading towards a lasting peace and relations had warmed between France and Germany.

In 1926, the Committee retroactively awarded the 1925 prize parallel to the 1926 award, both for the efforts to create a lasting peace in Europe. They did not go back and give more awards for 1923 and 1924, because the Committee felt was no reason too, and that there were not enough suitable candidates. It is worth noting that some of the people nominated those years would go on to win in other years.

The best answer is that the Committee chooses not to award the Peace Prize some years to make a statement. There are likely people working very hard towards peace all over the world, but the Committee feels that not enough people are working towards peace, or that the world has become complacent and accepting of war. To call attention to this fact they choose to award the prize to nobody. This can be seen in later years as well.

Through 1931, the Committee awarded nearly every Peace Prize to people who were working for lasting peace in Europe. By 1932, it was becoming clear that peace would not last in Europe and the Committee granted no award due to what they call a lack of suitable candidates. The awards given from 1933, after the rise of Hitler, to 1938, the outbreak of WW2, were largely given by the Committee to people who opposed the rearmament of Germany or supported the League of Nations. No awards were given from 1939 to 1943. Gandhi was obviously working towards peace during this time, but the Committee awarded him nothing, and it is likely one of their largest oversights.

Source: The Nobel Peace Prize and the Laureates by Irwin Abrams