Inconsistent framerate on Twitch stream-- No dropped, skipped, or missed frames...

[Reboprundgren]

Been trying to get a new streaming setup going but can't seem to hit a consistent 60FPS (720p) on my Twitch stream, despite several days of troubleshooting. The game runs perfectly smooth on my end-- My CPU (i5-8600K) & GPU (GTX 1070) usage sits comfortably below 70%, and the OBS stats window shows no issues with rendering, encoding, or dropped frames... But my stream still has extremely frequent framerate dips. Can anyone offer any insight on this?

LOG: https://obsproject.com/logs/hZ6xyJ9NN7jFxFKl
SCREENSHOTS OF SETTINGS/STATS: https://imgur.com/a/WY4B2GU
TWITCH VIDEO SHOWING FRAMERATE ISSUE: https://www.twitch.tv/videos/697901731 (Framerate issues present at beginning / Clears up @ 0:40 / Framerate issues very noticeable @ 3:55 onward)

A few other details that might be important:
-Issues present with all encoders - x264, NVENC, & NVENC (new)
-Advanced > Network > Dynamic bitrate makes the issue worse
-Issues present with both OBS & StreamLabs OBS
-Disabled Windows Game Mode, Game Bar, Game DVR
-Drivers are up to date
-Tested Twitch servers with R1ch's TwitchTest.exe... No issues
-Tested Twitch stream with Rich1's Twitch Analyzer... No issues
-Capping frames globally at 60FPS with RivaTuner
-Running OBS as Admin
-Running OBS in Performance Mode (No stream preview)
-Running OBS with Process Priority set to HIGH
-Download/Upload speed is 100Mbps / 6Mbps
-Bitrate set to 5000, have also tested 4500-- Issue present with both

I'm at a loss here... Any help that folks could offer would be greatly appreciated!

 

[Reboprundgren]

It's been a few weeks, & I've fresh-installed drivers, applications, games, turned off all my overclocks... Still no luck with this.

Does anyone have ANY idea what could cause framerate issues on Twitch, even though OBS reports no dropped, skipped, or missed frames? It's driving me insane here.