Page Templates - Liquid formatting

I have created a template which requires a lot of liquid - there is a block of 75 lines of it. I formatted it all to make it easy to edit, consistently indented, etc. I then saved it successfully. I went to the code editor to copy a few lines from a list layout. When I returned to the template code, all formatting had been lost and the 75 lines of liquid had been compressed into a single line. See the before and after images below. It happens every time I switch to another area and makes future editing very difficult unless I reformat it all.