That’s because communism was never supposed to be a thing you just implement and was never meant to exist alongside other ideologies.
Communism as first described by Marx and then later expanded upon by other theorists is merely the inevitable outcome of a global society that has overcome scarcity, moved away from late stage capitalism and values things like workers rights, equality and standards of living.
The biggest divide between communists is usually how we get to that end state. Do you try to ignite a global violent revolution against capitalism, seize the means of production by force and then use dictatorial power to try and force society towards it, like the Soviets did? Or should we make incremental changes over time though existing Democratic channels like democratic socialists? Or do you seize the power for yourself, run the country like a monarchy and claim you’ve achieved communism?