have you tried the actions on the BTS, rather than the TCUC ? Locating the SDCCH ts on another ts ?
Abis trace would show the contents of the channel requests which are subsequently lost (cause estab, timing advance,..). But I’m not sure you’ll find anything interesting here… who knows, you still can try 🙂
Can you please check the main usage of the SDCCH Request (MC02 x) : loc upd ? MOC ? MTC ? SMS ?
During the fail time, do you notice anything different about this distribution ?