It seems that audit is recording an errno of EJUSTRETURN instead of 0 for calls to execve(). This makes an audit policy with +ex ineffective.
header_ex,301,11,execve(2),0,::1,Sat Dec 28 12:10:13 2019, + 102 msec
return,failure: Unknown error: 201,4294967295
I suspect D13180/r326145, but haven't investigated further.