No ve.direct communication with MPPT 150/45 and Cerbo GX

My SmartSolar MPPT 150/45 won’t communicate with my Cerbo GX.
In addition I have two MPPT 250/85. The two 250/85 and the 150/45 are connected via a isolated vedirect<->usb converter and work fine except the 150/45. If I connect the 150/45 directly via ve.direct to the Cerbo its still not showing up. I tried different cables. Even with an original cable from Victron the 150/45 is not showing up in the device list.
One of the three ve.direct ports is used by a SmartShunt which works fine.
If I connect one of the 250/85 directly to the Cerbo it show up in the list.

Is there a way to troubleshoot this problem via ssh on the cerbo?

The MPPT is running firmware 1.64 the Cerbo 3.60~78 (with factory firmware and updated stable firmware I had no luck, so I tried the latest and still no luck - everything else works fine).

Thank you in advance for any help.

(short info about my setup: 2x 15kwh lifepo4, 2x MP2 5000 in parralel mode, 2x 250/85 and 1x 150/45 charge controller, “offgrid” with no ac in connection, load and some micro inverters on ac out)

Whilst maybe not a total solution to the debugging problem, if you connect to the cerbo via ssh, you can run a program called 'dbusspy’which will let you know if the ve-direct interface is receiving data.
An alternative - if you have a ve-direct >> USB cable is to plug that into a laptop, and see what is coming in in a terminal window. this should show the text broadcast from the MPPT.
serial format is baudrate=19200,parity=serial.PARITY_NONE,stopbits=serial.STOPBITS_ONE, bytesize=serial.EIGHTBITS