While submitting a request for catalog item that runs on a Flow have you encountered discrepancy while running it and then Testing it. Like when you submit a request the intended flow does not run as expected but when you Test it from Flow Designer Test functionality it runs as expected.

This is because when you run a flow from the Test Ui action in Flow Designer, it runs as 'System'. When it runs from a submitted catalog item, it likely runs as the user who submitted it, unless the flow properties are configured differently. It's possible that the user who submits the flow doesn't have the roles / ACL permissions to perform some of the actions. You can remediate this by adding a role to apply at runtime.

This can be done by going to Properties > Run As.

More about it : Create a flow with roles