If you supply the plain articles (text content) to APM, it can format them. Tthe outcome depends on the APM formatting settings.

Article elements formats

The article elements formats are always ignored and the shape formats applied instead.

This requires that the general preference (Edit > Preferences > Extra > General > When Linking) Keep Local Formats is ticked.

Article elements styles

The article elements styles are applied on the element if the Auto-Apply Styles preference is ticked. The original styles and tags (if any) are removed, before applying the styles, specified in frames parameter.

Note about styles and shape formats

In order for the styles to work even when the formats get applied from the library shapes, the styles MUST BE AVAILABLE in every format, applied on the library shapes.

An example: in your headlines, you use the style "RedH" that stands for the "red highlight". The headlines can be paginated in headline boxes of, let's say, 73 shapes in various object libraries. Those 73 shapes use 48 different headline formats. To all those 48 headline formats you must link a library of styles that contains the definition the RedH style. Otherwise, the text formatting error will occur and the headline will not be properly formatted.

See also

APM and preformatted text