This process is working just fine. I had another defect in my report, where i passed on the original HTML template to CL_GUI_HTML_VIEWER, rather then the version that i had updated URL for my image.
Below is a high level flow of my report:
* Load Data CALL METHOD html_viewer->load_data EXPORTING subtype = 'html' IMPORTING assigned_url = lv_url CHANGING data_table = lt_html EXCEPTIONS OTHERS = 1. ... * Show Data CALL METHOD html_viewer->show_data EXPORTING url = lv_url EXCEPTIONS OTHERS = 1. ... * Attach Images to HTML Viewer CALL METHOD html_viewer->load_mime_object EXPORTING object_id = ls_image-objid object_url = ls_image-url EXCEPTIONS OTHERS = 1.
You can see i even "show the data" before loading the mime objects, although this may not make any logical sense, it just happened this way, as i added the image capability as an add-on and it would require more signficant changes to execute this in "logical" order.
You can also check SAP's samples which should be available in you system: RSDEMO_HTML_VIEWER