This happened to me with version 12.00a. Today I upgraded to 12.10a but that hasn't brought any changes relevant to this issue.
Previous week I decided to put japanese/chinese content in some HTML files. I converted them ASCII->UTF-8, copy/pasted the Asian text from MS Word and it worked. The asian text displayed and was saved corrrectly, and I was happy. Now, without any change in the setttings, UE shows empty boxes (squares) instead of Asian characters. I've always used Courier New (the default) font set, it worked with that and now it doesn't.
My question is how to solve this AND keep the default Courier New font for non-Asian characters? I know that if I change the font to something different (like Arial Unicode and many others), the Asian characters are displayed OK, but let's say I'm attached to Courier New. Is it possible at all that I was using Courier New when all things worked fine - if I'm not mistaken then this set doesn't even include Asian characters? If not possible, then how did it work? Did UE use a different font for kanji/kana or it simply wasn't Courier New?
Codepage/locale changes didn't help, at least I couldn't make things work. File type is UTF-8 as mentioned above.
Another solution that I could accept is a font type which looks exactly like Courier New but supports Unicode.