Troubleshooting 101: Try to narrow down the source of the issue.
On the E682 config screen, change the test pattern to 1,2, or 3.
That should make the lights all go to a single RGB color. Change back to 0 to turn off the lights.
If that all works then your lights and the E682 are all ok. I don't think the issue is with the E682.
Remember a universe has 512 channels. Your config for bank 1 has 200 physical lights, that's 600 channels.
With 512 channels in universe 1, you'd need to use 88 channels from universe 2 to address all 600 lights.
Why does the E682 config have Universe 2, channel 90 as the last channel instead of channel 88?
(This is a rhetorical question of sorts)
Answer-You can't use channels 511 and 512 for RGB, Pixel 1=Channels 1,2,3 and Pixel 170=508,509,510
You say the issue is with Pixel 171 which is in fact on your 4th string, 20 pixels down the string.
Change your xlights config for each universe to end a channel 510 instead of 512.
99% sure that's what will fix it.
Let us know how that works.
Steve