ISSUE
When running a workflow that contains an "Assign a task" action, the workflow might hang on that action and not report any error, even if the user account is valid.RESOLUTION
Review regular expressions for a string field that is empty or has a NULL value and add a "Run If" action so the regular expression runs only if the String value input is not empty. ADDITIONAL INFORMATION
This issue occurs when the "String" field of a "Regular Expression action" contains a value that is NULL or empty.