Consecutive LED Strips not Lighting Right

[Angelasfliver]

Got 4 tracks of 12V WS2815 strips installed in a room in the basement connected to a PB v3 in the utility room 10 ft away. 239 pixels per track for a total of 956. (see photos). Let’s call all ends on the left A1, B1, C1, and D1 and on the right A2, B2, C2, and D2. All strips are powered individually at points A1, B1, C1, and D1. The data line zig zags and hits A1 first then connects A2 to B2 then B1 to C1 then C2 to D2. Track A works beautifully. All pixels at full brightness and respond to all patterns perfectly. Track B lights up fully but with random static pastel colors, Track C lights up with random, but more saturated colors about 1/3 of the way, and the rest of track C and all of track D are dark.
It almost behaves as though it’s suffering from voltage drop, but each line is connected back individually to the 12V 40A power supply. Is it a data problem? Anyone have any ideas?

Wish I could post a couple more pics, but it looks like I’m only allowed one

[Ungliovert]

It could be a voltage drop issue, but since you've connected each line back individually to the power supply, let's explore other possibilities. One potential culprit could be a data problem. Double-check your connections and make sure the data line is properly zigzagging and connected in the correct order.

[Jancasibr]

Hey, thanks for sharing your LED strip installation journey! It sounds like you've been through quite a troubleshooting process. Kudos to you for your persistence in finding the issues. The electrician's misunderstanding and the bad segment of the LED strips must have been frustrating obstacles. By the way, I'm also in the midst of renovating my house and came across LED Strip Kits that might be suitable. Since you've dealt with LED strips firsthand, maybe you can help me pick the right kit. I found their website and here is the link.: https://ledmontreal.com/led-strips-without-аccessories/.