When using catalyst without a CIB - i've notices that there is some spurious DMX on the first 10 (or so) channels. If you check out the CIB DMX diagnostic screen - the values on the relevant channels can be seen.

Problem is - if you choose to default a layer after manually changing it in catalyst, by enabling a DMX input starting at 001 with no CIB attached - it doesn't put eveything to 0 - it puts this random DMX state on to the layer, which is really difficult to figure out what it;s doing....

(if you choose to blank a layer by selecting Artnet instead of CIB - then it gets round this issue if you have no CIB connected)