I know this is an ancient thread, but I am having basically the same problem. The text only shows on the very first string of lights, and adusting the starting position up, down, left or right doesn't make a difference. The text works great on a matrix, but not on my mega tree. If the OP figured...
I am working on my first Christmas display with addressable pixels. It will be simple with a small mega tree, LEDs outlining the front overhang (soffit), perhaps a couple of arches, a couple window outlines and one P6 LED panel matrix.