Hans, in Friday's beta, core-sec.tex line 767 has
\edef\levelstring{=\flistsectionseparator\@@filternumberpart[#1]\sectionseparator}%
which fails not knowing what \flistsectionseparator is. Reverting to
\edef\levelstring{=\sectionseparator\@@filternumberpart[#1]\sectionseparator}%
works but may not be the intended effect.
Duncan