I did a project last year that had 8 LED strips fed by a Teensy 3.2 + OctoWS2811 shield beautifully. I am adapting the light fixtures for a new project now, and seem to have a problem where only half of the LEDs (strips 1-4) are driven at once from the OctoWS2811 shield (each set of 4 has its own 12V, 1A power supply). This problem manifested while adapting new code, but also manifests with the old code and BasicTest sketch included with the OctoWS2811 Arduino library. I didn't change anything in the programming or the wiring, it just sat in storage.

Things I've tried to troubleshoot so far:

Tried different power supplies. Either power supply I'm using works to drive the first strip.

Tried feeding the jack for strips 5-8 into strips 1-4. Strips 1-4 now have the part of image that 5-8 should be displaying. So, there is no fault between the Teensy + OctoWS2811 shield.

Made sure strips 5-8 weren't burnt out or faulty. I was able to test them with the data from 1-4.

Checked the strips to make sure they are receiving power. A voltmeter shows they're getting full voltage at the contact point between my wiring and strip.

Tried making an new CAT-6 breakout. Used a fresh cable to break out the signals from the shield's bottom CAT-6 jack, wired the same way as the old one. Still no good.

Any ideas???

EDIT: Sorry, I guess this should be in the Technical Help forum. Please feel free to delete it as I reposted it there.