I can't seem to diagnose the issue, but there's some sort of problem with the font tag.
Applying a font via manually typing it in or using the button seems to produce the same result.
If I write a new line of text and add a font to a portion of it, everything works as expected. However, if I apply a font to an existing line of text, nothing changes.
See "Quick Match" versus "Thoughtfulness" headings in my O/O thread. They have the same BBCode applied, and seem to have the same nesting*, but they display differently - even when using a cache-refresh reload.
* i.e.
<span class="bbc_size" style="font-size: 16pt;">
<span class="bbc_font" style="font-family: veranda;">
Any idea what the cause might be?