This problem only seems to happen in the WYSIWYG editor in Syllabus.
When creating a new item, I typed HTML tags into the WYSIWYG editor but I was NOT in the "view source" mode.
I clicked on Preview. It showed my syllabus items with the HTML tags unparsed (it still showed "<strong>" intead of bolding the text).
Then, I clicked on Revise. I went back to the WYSIWYG editor, but now my HTML tags had been parsed (so the text now appeared in bold).