Dreamweaver 2018 - Folded Code Keeps Expanding

I'm an "average" Dreamweaver user, just switched over from CS6 to Dreamweaver CC 2018. Working on a Mac OS 10.11

In CS6, I was able to collapse (fold) code chunks and - unless I switched to a different computer to work on the same file - they would stay collapsed any time I opened the file. More importantly, they stay collapsed while I was working in that file - allowing me to cut and re-order code without anything popping open. They would only open if I targeted content within the collapsed code, but would collapse again when selecting a different target.

Now, in CC 2018, I've collapsed code numerous times yet they pop back open at seemingly random times. Sometimes the collapsed code would "screw up" in that one or two lines would come out of the block while the rest remained collapsed. I have been able to force code to pop open simply by adding a line above the collapsed code. It seems that any time I edit content code pops open below and sometimes above.

I've tried Split Design and Split Live View modes, I've tried Code View mode only, I've tried code that doesn't contain errors or warnings, I've also tried modifying the minimum number of lines for folding code and selected lines manually rather than by tag.

Wondering if this is a bug, or some simple preferences check box I'm missing. Seems dumb to have collapsible code option that doesn't stay collapsed when working within the file.