Hello Nono15,
I have similar setup as yours (OC FMC v2, PMDG NGX, FSUIPC v4.86) and as I am using your instruction to get FSUIPC to recognize but have been unsuccessful so far. Nothing shown when I pressed key "A" from CDU in FSUIPC Key Presses tab. Encoder_keys shown the corresponding value of the pressed key in Last Key field. Likewise the SIOC Monitors shown the same value for the same pressed key.
I edited the encoder_keys.ini to send (like yours) Cntl+F10 when pressed the A key on the CDU. I also deleted all buttons/keys and control axises assignments from FSX.
I am running both sioc.exe and encoders_keys.exe when doing the FSUIPC assignments.
Thanks in advance for you help,
Vince