I've attached the xLightsProblem.zip file.
The 64001 number appears many times in the "ModF9B.tmp.csv" file but nowhere else. Something to do with the Start Channel assignment (some are Absolute entries, some are "follows xxxxx" ) but none use Universe designations.
My network definitions are minimal and "NULL" because I manually configure my controllers.
As I said, this doesn't appear to cause any problem and has probably been there for a long time, I was just looking at Warnings.