Try switching to the bp-legacy theme, does it do the same?
		
	 
	
	
	
 
		
			
	
	
		
		Yes it does.  The odd thing is it only loses the header formatting on a groups/group page?
		
	 
	
	
	
 
		
			
	
	
		
		Can you try deactivating all other plugins apart form BP? Does that fix it?
		
	 
	
	
	
 
		
			
	
	
		
		Deactivated all plugins, except BP, but still loses header formatting, Groups>group page?
		
	 
	
	
	
 
		
			
	
	
		
		Here the best fix I could come up with:
Appearance > child theme > style.css
.single-item.groups .custom-header .custom-header-media {
    position: absolute !important;
    top: 0;
    left: 0;
    height: auto;
}
I don’t like using !Important to override css does anyone have any more feedback or ideas on this or a more artful solution?