It is most likely a bad connection between the two sides of the print. All 7135 should be connected in parallel. Try with an ohmmeter or a continuity tester between corresponding legs of one 7135 on the upper side and one on the lower side and repair the missing connection (if any).
The input and output to/from the chips on each side are connected by the tiny holes(vias) in the board. If through a manufacturing error, those holes did not get plated, you will only see the output from one side. Measuring the resistance between corresponding legs on opposite sides will verify this. It should be zero for both Vdd and led-. If that is the problem, jumpers to make the two connections will fix it or you could send them back for replacement.
Edit- there appear to be 3 vias in question. Ignore those connected to the stars. In the first image at ~ 10 o’clock are 2 vias in line with the red arrow. The one toward the center of the board is Vdd and the mcu uses this trace to turn the chips on and off(pwm signal). The one toward the edge is the output where the current from the led is dispersed to the chips and through them to gnd. At ~ 1 o’clock is another via that connects other chips to the output trace. If you look carefully at the images you can see how the vias are used to complete the parallel connections of the chips. Some of the traces pass under the chips to do this.
Also how big are your wires connecting the led to the driver ?
I have wires made of 5 thin wires, and 7 thin wires. I currently only use the one made with 5 as it is more flexible and easy to solder on the board. But I am wondering if this is big enough
I am really wondering how you guys succeed in getting 2.8 or 3A, because I have now 3 drivers that should give 2.8A each, and I can’t barely get 2A…