Issue with SK6812 LED Strips: New Addition Not Working

I am using three SK6812 LED strips, each with 300 LEDs and 5 meters in length, totaling 900 LEDs and 15 meters of strip. The manufacturer’s specification indicates that the strip consumes 11.52W per meter. My power supply is 12V and 15A. Until today, I was using two strips with 600 LEDs, connected in series, and they were working perfectly. However, I recently added another 5-meter strip, and for some reason, this new strip is not working. I conducted a test by connecting only the new strip, and it worked perfectly. My controller is an ESP32 S2 with WLED 0.14.2.

Any idea what might be happening?

You need power injection. You can’t power all those LEDs with only connecting power to the beginning.

Also your pic does not show common ground to your Esp, LEDs, and LED power supply. You need that.

In addition to power (very likely), you also have to update WLED’s configuration to drive a larger number of LEDs.
Config->LED Preferences->Hardware Setup.