I have found that NWare 1.4.1 and NWare 1.4.2 incorrectly configure the CABs serial bridging network.
The problem manifests itself as incorrect TX and RX MAC address values in the Serial Bridging Network block and CAB RS485 settings.
Most times serial bridging just won't work. Paging stations show no network and the Q-host shows no RX activity.
Sometimes paging stations will be recognized by the Q-Host as online but remain inoperative. Selecting a valid page code and pressing the PTT button shows no activity in the Q-Host log. A normally operating system would show a page request as soon as the PTT button is pressed.
NWare/firmware 1.2.6 do not exhibit the behavior.
Files generated in NWare 1.4.2 can be made to work in NWare 1.2.6 but the Serial Bridging Network block must be replaced with one from 1.2.6 and the file deployed from 1.2.6.
NION firmware must be version 1.2.6. Attempts to deploy from NWare 1.2.6 to NIONs running firmware 1.4.x yielded erratic operation of the serial network.
Similar results were obtained by deploying from NWare 1.4.2 to a NION running 1.2.6 firmware.
It is noteworthy that in order to replace a bad device in NION, one must first drag in a new block before deleting the old. I have noticed that if I simply delete a device and drag in a new one, the new one gets the same device ID as the old device and inherits the same problems. So far I have only seen this in Cobranet related devices.

That last point might explain a few things!!

Ivorr, appreciate your findings on this subject.
I was going down the same line on Friday morning and had Serial Bridging working in 1.2.5, 1.2.6 was my next call before i had to flee from work early. I suspect 1.2(when CM was integrated with Nware) to 1.2.6 will work fine, it's like you have already said it's 1.4.1 & 1.4.2 which pose the problems.
Did you test 1.4.0?

Engineering has duplicated this and is working on a fix.  Shouldn't take too long...