Button icons moving

Hi I have used a button with an arrow icon.  The icon is to the right of the text in the button.  When it is published the arrow moves - sometimes over text and sometimes outside of the button. I have also noticed that although all the text and icons are white sometimes the icons show as black.  They are still white and to the right in the various inbuilt states.  I thought it was a quirk in 360 Review but it is also happening in the LMS.

I will attach a screen capture the next time this happens - it happens randomly.