it shouldn't be a problem to publish images in the 'content' section.
Does debug output give any useful information?
You could check some database tables to find out if the search words are in there - have a look at ezsearch_word and ezsearch_object_word_link.
You might also try to update the search index by script, see http://ez.no/ez_publish/documentation/development/scripting/supplied_scripts/update_search_index.