[otrs] How to disable all unlock timeouts

I'm a bit embarrassed that I haven't been able to find all the relevant setting(s) myself but... I haven't :-( I want to make sure that no locked ticket is ever unlocked by the system as a result of a timeout - so that only Agent actions can result in an unlock. I've searched in SysConfig for every combination of "(un)lock", "time(out)" and "auto(matic)" I can think of, and changed several settings... but it still keeps happening. I've played with settings related to Notification of the timeout unlocks etc... but haven't been able to stop the actual unlocking. The undesired event causes an "Agent::LockTimeout" notification. What critical setting am I missing? (fyi, v3.3.6). Thanks, MikeM