I have a test list set up with a "Title" field and an "escape value" field (single line of text field), and then a workflow that runs when an item is added or updated. The workflow takes the value of the title field, performs an fn-XmlEncode function on it, saves it to a text variable, the updates the item's "escape value" field. The test is indicating that the function fn-XmlEncode truncates a string containing a comma. If I enter "Hello, world" in the title of a list item, the "escape value" field ends up with simply "Hello". Am I doing something wrong here? Here's the setup with a screen shot of the results:
Workflow view of the workflow
The build string action escapes the title field and saves in a variable.
The update item action updates the "escape value" field with the variable value.
And here is the result for different strings. Comma seems to truncate the string and of course not encode the comma.