Solution:

If you are connecting two of the 855-19752  Single Strand Fiber units, indeed you will have trouble, because Single Strand Fiber is based on two different wavelengths transmitting/receiving over the same strand of fiber. The media converters will only transmit and receive on their designated wavelength. As a result, you will need a mated pair. Right now you have two left shoes. You need a left shoe and a right shoe. More specifically, the 855-19752  is the IE-MiniMc, TP-TX/SSFX-SM1310-SC (1310xmt/1550rcv) with an AC Adapter is meant to transmit at a 1310 wavelenth and receive at a 1550 wavelength. In this case, the two IE-MiniMc units are unable to communicate because they are both trying to transmit and receive on the same wavelength.