New Pylontech US 3000C not syncing with existing bank

I have an existing bank that has been operating for around a year (currently 1x US3000C and 3x US3000 [not sure, around 2 years old]). Rest of system:

  • MultiPlus-II 48/8000/110-100

  • 2x BlueSolar Charger MPPT 150/45 (each with 6x 330W panels)

  • 1x SmartSolar MPPT VE.Can 250/100 rev2 (8x 550W panels)

I have a I recently purchased 2 more US3000Cs, and installed them as master, 2, with the older batteries being 3, 4, 5 and 6. They have been in the system for 2 weeks, but they do not sync. They are still at 44%, as per the day I installed them (not one cycle). When they are in the stack, the Venus see 6 batteries, with none giving any errors. They just do not charge. When I install them alone in the system (other batteries not connected with any wire, not even earth), they also do not charge. Venus see 2 batteries, but Solar system does not work. When I set the state of charge, the batteries do not charge. It does not use solar to charge. And when I remove municipal power, solar goes down, even with sufficient solar (I get around 5 - 6000 W during the day).

Anyone have an idea what I can do? Should I update the firmware of the 3 US3000Cs?

How do I communicate with these to see what is happening, can I buy a communication somewhere or from someone ?

Whereabouts are you?