Ah i just posted few hours the same 
now i see your topic, which i could reply for the same. I used configurable SFP Modules, it has nothing todo with the brand. It is an implemention thing.
I have also a strange behavior, when I put the 155 Mbit/s module inside SFP1, nothing is happening, tjhe other site is not recognizing any LWL Signal. When i put the transceiver modul in SFP2, the other site recognize a “Link” (LED indicator is green and ON), but not teltonika TSW2X2