Monitor your VRAM, you're running into a known issue with MW where it's causing issues with other hardware accelerated programs (including OBS, and even Chrome). If you are running into an issue where you're running out of VRAM, try lowering your graphics settings (specifically texture resolution).
On the OBS side, I would recommend disabling Look Ahead and PsychoVisual tuning.
I would also recommend turning Game DVR off, and making sure you don't have the Nvidia Highlights enabled in-game... just trying to make sure none of this is caused by trying to use too many NVenc sessions.
Just got this today:
19:58:10.441: ==== Streaming Start ===============================================
20:15:33.234: User switched to scene 'ZOom'
20:15:48.102: User switched to scene 'Scene'
20:50:57.278: User switched to scene 'ZOom'
20:50:59.876: User switched to scene 'Scene'
02:56:52.414: error: Failed locking bitstream buffer: invalid param (8)
02:56:52.414: [NVENC encoder: 'streaming_h264'] nvenc_encode: Error encoding: Invalid argument
02:56:52.414: Error encoding with encoder 'streaming_h264'
02:56:52.414: [rtmp stream: 'adv_stream'] Encoder error, disconnecting
02:56:52.415: Output 'adv_stream': stopping
02:56:52.415: Output 'adv_stream': Total frames output: 1507104 (1507292 attempted)
02:56:52.415: Output 'adv_stream': Total drawn frames: 1506929 (1507356 attempted)
02:56:52.415: Output 'adv_stream': Number of lagged frames due to rendering lag/stalls: 427 (0.0%)
02:56:52.415: Output 'adv_stream': Number of dropped frames due to insufficient bandwidth/connection stalls: 188 (0.0%)
02:56:52.416: warning: 2 frames left in the queue on closing
02:56:52.418: ==== Streaming Stop ================================================
02:59:25.775: adding 23 milliseconds of audio buffering, total audio buffering is now 46 milliseconds (source: Mic/Aux)
02:59:25.775: