Has anybody experienced problems adjusting the monoriser post?

In my case it is completely stuck, I cannot even remove the riser post clamp. In fact, the clamp was torqued to 4 Nm only (I remark that 8 Nm is the value recommended in the assembly manual) as I already started hearing some 'creaks' as I tightened... any ideas on how can I loose the monoriser without disassembling the handlebar, please? Maybe there's something wrong in the setup but everything was perfectly assembled according to the manual, including carbon assembly compound!

Thanks!