I have contacted James and he is going to look at this again shortly with another tester, yes my apologies that was a typo I meant to say it flashes even if the 'Chauvet Colour Band Pix' battons are plugged directly into the desk with patch leads - bypassing all of the infrastructure cabling and 'Showtec DB 1-8' splitters ruleling out the environment. There are 7 fixtures on the DMX line and they are all the same with different addresses but flash at the same time even in blackout. I believe the tester was a swisson dmx tester. The issue started since upgrading to 7.9.4 from 7.9.3, I tried rolling back but it did not fix the issue oddly so it might not be fully rolling back some of the firmware? The infrastructure cabling is under the maximum length.
When we tested the smaller FLX S24 that we have in a studio also on 7.9.4. it also had the DMX anomalies that James saw however it was still within DMX specification I believe.