I am building a third sign that has 144LED per meter or 1/4 inch LED spacing. The first tests indicate lots of bad connections. The issue is likely in the LED strips being shipped wrapped on a spool that is too small.
In this first picture the middle row quits about 3/4 the way across the sign. One of the pixels in the "U" is red but that is hard to tell in the picture.
In this next picture the bottom right corner LED is out. The third row down is a different shade of blue but you cannot see that in the picture.
here is the video of the first test. Some of the issues went away during the video indicating they are caused by bad connections.
When I tried to run all 16 rows by wrapping the top 8 rows back to the bottom 8 rows this is what I got. Only 3 of the bottom 8 rows came to life.
I finally was able to fix all of the bad connections. I even replaced some of the strips to get it to work. There is a yellow LED that is red in the picture.
This picture shows that there are still some bad connections!! After fixing many many of them!