A330 - No way to enter a flight plan

Ok, I am reaching the end of my capacity to fix this. I want to set up a flight plan for the A330, but I find no way that works.

Typing it directly in the MCDU, after doing the INIT page, I type in the departure, then as soon as I add a waypoint after the last departure waypoint (or before destination) I end up with a looped flight plan (in order: departure waypoints, destination airport, and departure waypoints again, and impossible to remove a number of them to restore order).

Simbrief, after having all linked correctly, inporting in the in-cockpit EFB on the left correctly, if I try to send it directly from the Tab EFB to the airplane, it freezes the MCDU and most of the cockpit's elements, and I have to restart the flight.

The simulator's built-in flight plan system: if I send to avionics before the flight it does nothing, if I send after starting the flight it does the same as Simbrief: MCDU freezes.

Am I doing something wrong? Some of that looks like known bug, some of those look like they're not new at all in iniBuilds aircrafts, but is this airplane's navigation system useable at all? What workarounds are people using? So far, wasted a good 2-4 hours over the last few days and frustration is rising, so if it's not useable someone let me know so I will give up until there are updates