Sorry for revamping the old thread, but just wanted to confirm that this happens to me, too. I used effects 'Replace color' and 'Set color'. This resulted in strangely distorted sprites when placed on the layout - not only sprite font, but 'ordinary' sprites, too. I'm not sure, but there's a good chance that the bug appears only when you place a new sprite on the same layer with sprites that use aforementioned effects.
The 'remedy' was to disable 'Preview effects' in the project properties.