Is it synthesized hopp ?
I have ever meet this problem on the network, and my solution is move sdcch channel into BCCH TRX.
And I have recorded with K12 traces, and it was found that certain TS has problem,but I have swapped the TRX, still not solved.
Then I try to Change the COBA,because the certain TRX belongs to the same COBA (The COBA was flicker), but the result is the same..
Then summarize to customer that the backplane has problem….
If your problem like above, I recommend to try change the backplane, but ensure that all database is correct including hopping type and setting