'Set SLA' > 'For Milestone by Process Priority' Rule Action does not work with extended Incident data type. There are no (Error-level) errors in the logs at the time this occurs.

This works just fine when Incident data type is not extended.

This affects a ServiceDesk out-of-box rule in OnIncidentReceived ruleset which results in a newly created Incident having no SLAs.

Execution results for Ruleset [OnIncidentReceived]
Rule [1]: If [Any] Then [Set SLA][For Milestone by Process Priority(Initial Response)] Using [2 Parameters] AND [Set SLA][For Milestone by Process Priority(Resolution)] Using [2 Parameters] :: The conditions were met. 2 Failed Actions.
Rule [1]: Action Failed: [Set SLA][For Milestone by Process Priority(Initial Response)] Using [2 Parameters]. Error: No SLAs were created for 'Initial Response-'.
Rule [1]: Action Failed: [Set SLA][For Milestone by Process Priority(Resolution)] Using [2 Parameters]. Error: No SLAs were created for 'Resolution-'.

Product defect.

This issue has been reported to Symantec Engineering and will be fixed in a future version fo the product.

Workaround:

Set the Priority before the SLA rule runs in the same ruleset:

[Set Priority][Using Impact/Urgency Matrix(Incident Impact/Urgency Matrix)]

After this, the problematic action works as expected.