See https://discourse.phabricator-community.org/t/files-uploaded-to-panels-dont-get-attached-to-object/3283.

Currently, "Text" dashboard panels don't export their content change as a Remarkup change, so secondary effects (like associating files and handling mentions) don't trigger.

To reproduce:

• Create a "Text" panel.
• Drag a file into the text.
• Save the panel.
• View the file, note it isn't associated with the panel.