This issue typically occurs when voice track placeholders haven't been placed in the clock scheduled for that hour, or the hour has already been scheduled into the playout log without voice track placeholders. To resolve this, check that your clock includes Voice Track items where presenters need to record (Manage > Clocks), verify the correct clock is scheduled for that time slot (Manage > Clock Schedule), and ensure the playout log contains voice track placeholders for those hours (Manage > Playout Log) after scheduling. If you've made changes to clocks after scheduling, you may need to unschedule and reschedule the affected hours.