Can't unassign Dbroot

Hi!
I'm testing with a mariadb server system in which I have 3 servers, two of them being Ubuntu 16.04 and the other one being Ubuntu 18.04.

I created my PM1 and my UM1 into the two Ubuntu 16.04 servers, and after I started the system I added the Ubuntu 18.04 server as PM2.
I know it is supposed that all the modules must be into servers with the same OS, but I just wanted to test.

At the begining everything seemed to be ok, everything was active.
When I tried to load some data to the database, the data was not being distributed accross the PMs (I have one Dbroot attached to each PM).

Finally I just decided to unmount the PM2 because it seemed not to be working.
I stopped the system and tried to unassign the Dbroot first in order to remove the PM2 later, but when I try this I always obtain the same error:

Segmentation fault (core dumped).

I tried to move the Dbroot2 to the pm1, because I thought maybe it was because to the PM2 and not due to the Dbroot2.
I am able to move the DBroot 2 from pm2 to pm1, but I am still not able to unassign and remove it, I get the same error.

At this point I just want to remove the pm2 and the dbroot2 from the system, I would appreciate any help...

By the way,
just in case, I want to ask you about the redistributeData function.
In the next days I will add a new PM to the system (this one into a Ubuntu 16.04).
Doing so and executing redistributeData start, will I be able to distribute my data between the old and the new PMs?
Reading the documentation I understand I will be able to do so but... I just want to be sure.

Thank you so much in advance.

EDIT!

Hi again!
I was updating some data to the mariadb during the weekend and now the tables are being redistributed perfectly accross the 2 PMs.
I don't know why, maybe it is due to the Dbroot movement I did or... I don't know

Anyway, It would be nice if you take a look at these!
Thank you in advance again!