For OmniStream units running the older firmware version 1.0.4 you must first step the FW up to 1.1.0 so they can be successfully updated to 1.2.6 and beyond:
1.1.0 FW Links
- single channel - https://atlonainc.box.com/s/lswn6s1u0he3y7ojxhwqdwg5kc4rep92
- dual channel - https://atlonainc.box.com/s/lp91hbfvffntncmn29lwv7syqelmzv80
After the units are on 1.1.0, they can then be upgraded to the latest OmniStream firmware releases.