Need some starting issue advice!! please

hello,
2004 saab Aero.

Suddenly started developing intermittent charging issues.
Got a Tech II and it shows no Code. However after it does not start, I got a plausibility T8 code.

Key turns and clicks to start. NO messages, Everything turns on as it should. I hear 1 click (like the starter wants to come on) and then nothing.
Battery tested (Load and Volt) all okay. Starter motor tested, all okay. Starter motor get required voltage upon ignition.
but it does not start.

Oddly enough, when I try to start it, the battery goes from 13.4 to 12.5 in voltage.

Next step is checking on the ignition key assembly. Hoping that is the issue.
However if anyone has any thoughts, please don't hesitate to answer.

Thanks.