I added a icon label and the haywire began. Resulted in random files showing status icons as their icons instead of for example a .txt file showing the notepad looking icon. To fix I had to replace foldercolors.oxc and colorgroups.oxc from a backup.
When I added the icon label there were existing icon labels active. I compared backup file and current with beyond compare. All entries for existing icon labels in foldercolors.oxc were removed somehow just by adding a new label with a icon only.
I tried to reproduce for a second time but wasn't able to.
My existing label icons have been set for months and working fine. When I added the icon label that triggered the random icons, that's all I did was add a label. I never applied a 'Label filter' or 'Wildcard label' to it.