Sorry that I didn't quite explain myself.
In disabling the auto-purge, I occassionally got RT LOG error I mentioned. On attempting to do so again, it would apply the change without giving any errors.
Once it did not give any errors, I assumed the auto-purge had been disabled. Then I ran the sequence jobs that call the multi-instantiated job, expecting to see all 10 (or more) logs, one per invocation id.
When I said that the results were negative, I meant that I did not see as many logs as the invocation id's.
Thanks