Conditional Content Breaking Apart

Hi all, 

I am using the new email designer and have built emails with conditional content. I’ve been noticing that sometimes when I save them and come back the conditional content is broken up into code sections. Whilst it isn’t the end of the world, it does mean I can’t make changes to the segment. 

Sometimes if I click [ctrl + z] whilst in the email editor, it all goes back to normal but the segments are called ‘custom’. 

Has anyone else experienced this or have any ideas about what is happening? 

Example below:

Thanks!