Icons overlapping text on buttons

Hi all

I have used inbuilt buttons with SL icons. The word Next with and arrow icon on the right.  Sometimes the next overlaps the arrow, sometimes the arrow moves outside the button and sometimes the arrow displays in black (its white) and there are no differences in the other states.  I thought this was a 360 Review but it is also happening randomly in the LMS version. 

I hope someone can help asap.

Kind regards and thanks in advance.

Jen 

PS  I have attached some screen grabs.