Automation fails to perform an action sometimes

Intermittent problems in executing an action are usually related to what is sometimes called a "timing" issue.  Automation runs FASTER than human interaction and, unless told to, does not take into account any queues from the application as to whether or not the control intended to be acted upon is available.

Please check the help documentation concerning "Waiting" for controls.https://support.smartbear.com/testcomplete/docs/app-objects/common-tasks/waiting-process-or-window-activation.html