Resolve 17.2.1 - 12G Optical Fiber transmissionfails if > 3m

Hi,
I have a
1. BMD Decklink 4K Extreme 12G - FW 12.1
2. BMD Teranex Mini Optical 12G to HDMI 12G - FW 7.1.1
3. 2 x BMD 12G SFP Optical Module
4. Multiple LWL in various Length and type
5. I get a stable image on Screen only with LWL < 3m - 2160/50p

I tested with the following optical fibers:
a) 3m Optical Fiber 9/125 Singlemode Duplex LSZH for SFP LC/LC - success
b) 10m Optical Fiber 9/125 Singlemode Duplex LSZH for SFP LC/LC - failed
c) 15m Optical Fiber Duplex OM4 LC/LC - failed
d) 15m Optical Fiber Duplex OS2 LC/LC - failed

Image on Screen is blinking with b) trough d)

Components 2 + 3 has been RMA't to BMD Germany and found as OK !

What to do next ?

And here is the story and how it ends with my optical Fiber transmission problem:

I thougth it was a LWL problem and therefore I ordered an additional LWL cable which is:
-15m LWL Premium Patchcabel LC/LC 9/125µ Duplex FRNC 1550nm
--> but it failed also

Then after while the Teranex Mini break down - it failed on power on.
I send it back to my dealer and got a technical exchange.

When I received the second Teranex Mini it failed as the first one when Resolve Project setting was 2160p50 - in the beginning I got a black display but after a while after frequent changes from 2160p30 to 2160p50 and vice versa it had the same behaviour like the first box the image on the display starts blinking when set to 2160p50 - when set to 2160p30 the image was OK and stable.

That was the point where I asked the BMD EMEA-support what to do.
Jurij Smirnov User Support EMEA tried to replicate the signal workflow and found the source of the problem:
--> It's the optical ports on the Decklink 4K Extreme <--

In his case the Port A fails on 2160p50 and the Port B works
and in my case the Port B fails and the Port A works with 2160p50

Strange - Problem has been adressed to the developers - I hope they can solve it with a FW Update
soon.