For all the good attributed to the progressive era, there was one major problem that surfaced. what was it?

The Progressive Era ushered the country towards a new further but led to one major problem, that of 'Too Much Government Control'

Explanation:

For many Americans, government interference or too much legislation was generally seen as an attack on their 'Freedom' and the 'right to pursue happiness'

However, the Progressive Era, a period between 1890s and 1920s, saw an increase political and social activism.

While starting out as a social movement, it turned into a political one, leading to many changes in the government, including introduction of new taxes, employment laws, business legislations etc.

each played a major role in ending the cold war.