I just resolved this EXACT problem in Word. Every time I tried to enlarge the picture past the half-way point horizontally, Word chopped off the right-hand side of the graphic. In my case, I had COLUMNS set to TWO immediately above the picture -- even though there was a section break between the columns and the picture.

I placed the cursor right above the graphic and set the COLUMNS to ONE (Page Layout, Columns). Now I can resize the picture to cover the whole width of the page. Word no longer displays only half the graphic.