The Process Engine processes do not start with the sw_error.log file reporting errors such as,

2018/09/12 11:32:00.518676(BG:3:5076:1::::pro:psulmain.c:84990:4857): 1946-Process failed to subscribe to events after 24 attempts

The corresponding dump file, for example bg01_180912_113205_1620.dmp, for the failing processes report the errors,

[T=00884]180912113201.926853:v001: iel_msq_publish_event (): CoCreateInstanceEx(): failed: 8000401a
[T=00884]180912113201.926862:T001: process_start_publish_status(): iel_publish_event() Failed. Retcode:-10
[T=00884]180912113201.926865:T001: process_shutdown():process_startup_publish_status() Failed. ReturnCode = -2.

The command "swadm EVLOOPBACK" is also failing which indicates an Event publishing issue,

Attempting to test event:
WARNING: Failed to send SE_LOOPBACK message.

All supported Windows platforms.

The 'failed: 8000401a' part of the message indicates an issue with the username/password identity calling the "Staffware Events".

This link provides some insight into the error code - 8000401a which is returned as 'CO_E_RUNAS_LOGON_FAILURE'.
https://blogs.msdn.microsoft.com/dsnotes/2014/09/25/com-client-failing-with-error-8000401a/

Check the user and password in the Identity tab of the "Staffware Events" are correct after rebooting the server and ensure the "Staffware Events" start correctly.

The iProcess Engine processes will not start with failed to subscribe to events errors in sw_error.log file