Some folded code will unfold when adding content to the source file. Folded functions appear to be most affected. It will not unfold all folded code, just a few below the line that was modified.

To reproduce the issue, enable all the code folding option under 'Preferences -> C/C++ -> Editor -> Folding', then open a source file with several functions. All the functions should be folded. Then in the middle of the source files (between several folded functions), enter in a new line (press Enter). Some of the folded functions below the new line will unfold.