The plugin does not run as a scheduled job

[benyrfg]

Hello, I have forked this plugin to modify articles selection by data time value in custom field (but it basically do the same as original plugin). I have an issue: The plugin works well when I run it manually by click on the "test run" button in the tasks administration. But when I set-up task job, for example every hour, it always end with error and the task don't run.

In the log file is:
INFO Task #1 'Transfer completed events' is in progress.
WARNING Task #1 is unlocked.

A created a topic on Joomla forum here: https://forum.joomla.org/viewtopic.php?f=833&t=1005967&p=3709714#p3709714

I would appreciate any ideas.