16:29:55.503: Output 'adv_stream': Number of lagged frames due to rendering lag/stalls: 27 (0.0%)
16:29:55.503: Video stopped, number of skipped frames due to encoding lag: 27/220495 (0.0%)
No rendering or encoding lag.
15:28:38.981: rate_control: CBR
15:28:38.981: bitrate: 3500
15:28:38.981: cqp: 20
15:28:38.981: keyint: 120
15:28:38.981: preset: hq
15:28:38.981: profile: main
15:28:38.981: width: 1280
15:28:38.981: height: 720
15:28:38.981: 2-pass: false
15:28:38.981: b-frames: 2
15:28:38.981: lookahead: false
15:28:38.981: psycho_aq: true
3500 is a bit low for 720p60 using NVENC. If you can increase to 4500 or the usual max for non-partnered Twitch, 6000, you should see an improvement.
That and change the color setting to 709/Partial.