Hmmm, that’s weird.
I have EmEditor on my notebook too, I edit a copy of that same file there too on a daily basis, and my install there indeed does have the option “Prompt when saving unicode as ANSI” ticked, but i don’t get any prompt there. 😕
PS. On my notebook, i don’t install beta versions, so there it’s the latest final 11.0.5. Only other difference is that on notebook i use the 64bit version, while on the PC it’s the 32bit version.