When you copy text from a window that has UTF-8 encoding disabled but decoding enabled it won't copy the decoded text, but the original undecoded UTF-8 text. Pasting it somewhere, even in another window that has UTF-8 encoding enabled, will result in the multi-byte characters to not appear as one character but the different characters it consists of in your usual encoding (I have multi-byte edit boxes enabled).

For example, copying "* Merley körde Avant Browser länge." will result in "* Merley körde Avant Browser länge." when pasting.

I found that if you go to View...Font...UTF-8 and set it to Display and Encode, check set as default channel font, and use default, and hit ok, this problem is gone.

Yes, as I wrote the problem will only appear if you don't have encoding of UTF-8 enabled.

Thanks this should be fixed in the next bugfix release.