If there is a problem with a type 1 font, so that xdvik needs to fall back to a generated PK font, then only the first instance of that font is handled correctly. For instances of the font at other sizes, the pk file is not generated, and characters are left blank. See the sample (plain) tex file. Other examples are available at the message thread at http://tug.org/pipermail/tex-k/2012-September/002423.html
Brief sample (plain) TeX file
This has been fixed in Version 22.86 (which replaced use of t1lib with the FreeType library).