Query List action returns null if the filter is an empty string
When using the "Query List" action in Nintex Workflow for Office 365, with a Filter that is equal to a variable that has an empty string. The query will return 0 results even though there are some item(s) with an empty string value on one of the columns.
Design the workflow as below:
Use the "Conditional branch" action to check whether a variable is empty or not.
If the variable is empty then use "Query List" with Filter = Is Null.
If the variable is not empty then use "Query List" with Filter = "Variable".