Quadro Sync - external Reference

I’m new to this ‘devtalk’ site, so I’m not quite sure if I’m correct here.
For a special purpose I need to synchronize a Quadro M6000 or K5200 connected
to a PNY Quadro Sync from an external source.
Everything seems to work fine, but unfortunately the Stereo output signal on
the 3-pin Mini-DIN connector on the Quadro graphics board is sometimes in phase,
but sometimes 180’ shifted related to the input signal, after enabling external
The external signal is a 50Hz rectangular signal (3.3V / 50% duty cycle) provided
on the BNC connector. Everything seems to be OK - as the indicators on the
FrameLock section of the ‘nvidia-settings’ tool (I’m using Ubuntu 18.04 LTS)
go green every time.
Is this a known issue?
Is there a know workaround for getting the same phase of the above mentioned
signals every time?
Is the RJ45 connector an option for getting rid of the above mentioned problem?
I found a pinout of the RJ45 connector in a document named ‘BD-06576-001_v01’.
Unfortunately the explanations are not very sufficient. Not every signal is
explained in detail.
Because I don’t want to send the Quadro Sync board to the ‘happy hunting ground’
(if you know what I mean…), I need some more information about that (when to
provide what signals on which pins and when to enable / disable what feature
before providing the signal(s)).
A request to PNY support offered me to forward the inquiry to this forum. I hope
I will get some more information here.
In case you need more information, please let me know.

Thanks in advance

Georg Glock