This is just for info as I have reported this to the Dev. team at CoffeeCup.

For other software I use I need to have the Windows "Beta Region Setting option for Unicode UTF-8 support" enabled.

Doing so causes some 'dashes' to be altered to — characters.
This then stops the page loading in the in-built viewer.
(External Browsers seem to work ok...)

But, really annoyingly the Search function will not find the — characters...

I have also found that Html Editor also "silently" makes changes on opened files - specifically PHP files in my case. It seems to remove "LF" chars and extra empty lines.
(This is not related to the above UTF-8 setting.)

Making ANY silent change is obviously a real problem.