I’ve got the same problem.
I’ve found that my printer STEPS per mm were non correct and prints came out slightly bigger than it should be (the calibration cube came out 20.20×20.18, instead of 20.00×20.00)
2 days of calibration and a lots of cubes later, I managed to get a quasi perfect cube of 20.02×20.03mm.
reprinted 2 pieces and works perfectly. Tight fit. Someway too much indeed…
Recalibrate the Steps per mm and it will be good.