The PATRACENMI parameter was defined twice; once next to the PKTANALYZER parameter, where it was set to NO, then again much further down than the rest of the related parameters, where it was set to YES.
Netmaster uses the last iteration of any parameter defined, so was trying to use the IBM NMI without the security permissions to do so, thus no packets were being captured.
Removing the second PATRACENMI parameter resolved the problem.
PKTANALYZER=YES was already defined.