Yes, it’s most likely to be a small error of how the data flow is passed through nodes. Check every node to see if there is an expression parameter that returns ‘[undefined]’ through both your workflows.
Can’t be sure without seeing the workflow though.
//Select all nodes in your workflow and copy them simply using
//Ctrl-C and paste it here in a preformatted text
You’re right—it might be a data flow issue between nodes. I’ll go through each node in the sub-agent and main workflow to check for [undefined] expressions.
Would it help if I share the relevant emailAgent and contactAgent workflows (triggered via Execute Workflow in the main assistant)? Sorry for my late reply but I appreciate the help.