I think the issue might be due to the fact that the front end token "GraphicsAlign" is no longer implemented in Mma v11.3. Some other tokens, present in earlier versions, are also missing. Which is a pity, as loss of functionality is never nice. But perhaps there is an alternative way, using the notebook interface, of resizing multiple graphics in a notebook to make them all the same size (same width, for example), without doing it individually, graphics by graphic ?