Unable to Scroll L-R

When zooming into a project (PDF/jpeg/image/etc) with either CTRL + + OR the zoom drop down, you are only able to scroll up and down on the document; there is no option to scroll horizontally (L to R). I found in the Adobe Express Community this response to a user: When zooming in, try holding the spacebar, left click and dragging your mouse to navigate the page. I hope that helps, but please let me know if it doesn't. This only worked for a moment, then I was diverted back to the center of the document. I have noticed this in other projects, but working in a different scale this is more problematic. Any advice would be useful!