Hi DreamWeb,
Welcome to
RP!
I'm glad you solved your problem already ..
What happened to you, isn't necessarily a bug...the colour used by the Diffuse Glow filter, is, by default, the 'Background Color' wich, in Photoshop, is, by default, white ....
If, while working, you change the Background colour to (for example) Cyan, and afterwards you use the Diffuse Glow Filter, the 'diffused' colour will be Cyan (see attachment)....
So, if this happens to you again, before resetting the Preferences, which affects everything, brushes, presets or whatever changes you have made to workspace, palettes etc., simply reset your Foreground/Backgorund colours by pressing the key
"D" on your keyboard.
Hope this helps....