Ok, had time to check this stuff again. Since yesterday the Acron plugin is disabled anyways (see: OJS page stalls - awesome delays ). Neither
php tools/runScheduledTasks.php plugins/generic/usageStats/scheduledTasksAutoStage.xml
nor
php tools/runScheduledTasks.php plugins/generic/usageStats/scheduledTasks.xml
were doing what should be done. However, I now enabled my fix again adding the line
$args = array("autoStage");
In plugins/generic/usageStats/UsageStatsLoader.inc.php and enabled my system-cronjob again. Now calling /scheduledTasks.xml is auto-staging and doing all the metrics as expected.
I’m very sorry not to find the “major” purpose for this issue, however, I hope that - for my application - this fix solved the problems.
All best,
Reto