This specifically occurs when I start a new paragraph, all font sizes are resized to a couple points above. I will select 12 point font and the window will automatically change to 13.6. The same occurs for other font sizes. I can only get 12 point font by selecting 10.5 which then becomes 12.
Are you changing the font size in your paragraph style or are you using the direct formatting from the toolbar? If the latter, the change will only apply to the selected text