Have you seen something that looks like what appears in the "Description of Work" field below in one of your Custom PDF Outputs? Any time you see just one line of text appear in a field (where there should be more) you may need to adjust the settings on the reference PDF you upload into ClearForms.
When you see the above (and if you're using Adobe Acrobat - on other PDF software the setting may be accessed another way) check the Options tab on the Field Properties settings. Check to make sure that "Multi-line" is checked/ enabled for your field. Once it is and you upload the revised PDF to the Outputs section, your text field should show the multiple lines of content that you expect.
Please note that there is not currently a way to have mapped fields be expandable to fit variable amounts of text - so be sure to create enough space on your PDF form for mapping to allow the amount of text you expect to be visible in the export.