ed does not join lines with ASCII text, with CRLF, LF line terminators

I am currently running Gnu ed version 1.18 in the Debian WSL on Windows. If I edit a file with the following encoding: ASCII text, with CRLF, LF line terminators or ASCII text, with CRLF, then ed does not properly join lines with the j command. Rather, it deletes the first line meant to be joined. This problem does *not* occur if the file is created in ed, but it does affect files that were created in other programs and are then edited in ed. The same problem is found in GNU ed 1.17. Is this a bug? How would one circumvent this problem?