Yettwasezmel 4 ɣef 5 n yetran

sɛur retrovertigo di Oct. 15, 2017 · aseɣwen yezgan

Works fine for me in TB 56 (current beta version). Only issue is speed. It took ~15 minutes for 170 emails to get copied from one account to the other - in one main and two subfolders. This was a first test run, we see how the next one goes.
FYI, my folder structure was:
[main folder]
....|-- [subfolder 1]
........|--[subfolder 2]