What mode are you using to connect to oscam?
How about trace logs (--trace descrambler,capmt) and oscam log with debug level 128 (dvbapi).
I did find an issue when I made changes for extended_cw support. Tvheadend only sends the full PMT on the first channel and not again. Not sure if the fault is with oscam or Tvheadend, but it can be fixed with a small patch to oscam. (if that turns out to be your problem...)