This can be very frustrating.
the MMUv1 has four extruders on the top rail, and they are in two pairs. each motor in a pair, rotates in the opposite direction to feed filament,
the two main issues are extruder numbering from the front of my printer, extruder1 is on the left and extruder 4 is on the right.
If you number them the other way, they will all turn in a reverse manner...
if there are any poor connections on the connectors, strange things will happen....
so my suggestions,
1, ensure the extruders number 1 ... 4 from left to right, looking at the front, so extruder 1 is nearest to the Rambo and extruder 4 is nearest to the powersupply!
2, disconnect and reconnect all 4 motor cables a couple of times to ensure good connections, do the same with the two cables from the stepper motor expander board, disconnect the connectors and reconnect to clean the surfaces up.
hopefully this will restore functionality.
I try to make suggestions that I believe to be well founded and safe,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions,
what you do, is YOUR responsibility.