Hi,
Yes that's it, checking the log the below
21:06:17.950: WASAPI: Device 'Microphone (Realtek High Definition Audio)' initialized
21:06:17.950: source 'Mic/Aux' enabled push-to-talk
shows that the mic is in the list but have you set a push to talk hotkey or set it to push to talk?
On another note you have the below when streaming with 2500 bitrate, this shows some bandwidth issues which will lag your stream along with the encoding lag at 59% which means your cpu might be over worked.
22:28:31.309: Output 'simple_stream': Number of skipped frames due to encoding lag: 54672 (59.2%)
22:28:31.309: Output 'simple_stream': Number of lagged frames due to rendering lag/stalls: 67 (0.1%)
22:28:31.309: Output 'simple_stream': Number of dropped frames due to insufficient bandwidth/connection stalls: 6036 (6.5%)
You then use a 1800 bitrate which help on the bandwidth but still you are having encoding lag
22:30:03.342: Output 'simple_file_output': Number of skipped frames due to encoding lag: 54675 (57.5%)
22:30:03.342: Output 'simple_file_output': Number of lagged frames due to rendering lag/stalls: 73 (0.1%)
therefore try a lower cpu preset like superfast or ultrafast as you have it currently on "preset: veryfast"