It seems it didn't give an error in the Flight Scene when i switched to a craft before the update. However it starting showing there as well in newly built craft.
Giving this error instead.
NullReferenceException: Object reference not set to an instance of an object
at Ratzap.FuseBox_Core.setTBIcon () [0x00000] in <filename unknown>:0
at Ratzap.FuseBox_Flight.OnGUI () [0x00000] in <filename unknown>:0
No, I'm not running Kerbalism.
Here's one of the craft files: https://www.dropbox.com/s/eouzk0m5ykbcvpm/Gemini.craft?dl=1
Though I could remark since updating Fusebox that it did change icon. It had a icon with bars before and now with the lightning bolt. If that helps in any way.
Keep up the great work!