Why are the pixels white all the time

This can happen if you accidentally connected the pixel data wire to the CK connector on the LeDMX4. The pixels will then think the clock signal looks like data and be ON all the time. This can also happen if you have WS2813 or similar pixel types that have a backup (labeled BI) input, and you connect this to the CK connector. BI should either be connected together with DI to DA, or to GND.