The Set "EXCLUDE_MACROS"  in "ViewMacroMarshaller" in package "com.atlassian.confluence.content.render.xhtml.view.macro" comprises of table macro names. Macros with names not in this Set are rendered outside of the table.

For example, col and colgroup macros are rendered outside of the table, which breaks the table.

Suggestion

• Make list of ignored macros customizable
• Add th, col, colgroup to the list.