I can confirm that this is similar to the problems I am experiencing. The problem was introduced between BETA 2012.01.02 19:23 and BETA 2012.01.11 14:58. (These are based on the gitorious revisions).

There were some betas released between these two, but they caused other problems which would stop the document compiling, so I can't narrow it down further. The following files were changed between these two revisions:

context\data\scite\lexers\data\scite-context-data-context.lua
context\data\scite\scite-context-data-context.properties
metapost\context\base\mp-core.mpiv
metapost\context\base\mp-grph.mpiv
metapost\context\base\mp-tool.mpiv
scripts\context\lua\mtx-interface.lua
scripts\context\lua\mtx-update.lua
tex\context\base\anch-bck.mkvi
tex\context\base\anch-pgr.mkiv
tex\context\base\anch-pos.mkiv
tex\context\base\buff-ini.mkiv
tex\context\base\buff-ver.mkiv
tex\context\base\colo-ini.lua
tex\context\base\colo-ini.mkiv
tex\context\base\cont-log.mkiv
tex\context\base\cont-new.mkii
tex\context\base\cont-new.mkiv
tex\context\base\context-version.pdf
tex\context\base\context-version.png
tex\context\base\context.mkii
tex\context\base\context.mkiv
tex\context\base\core-def.mkiv
tex\context\base\core-mis.mkiv
tex\context\base\core-sys.mkiv
tex\context\base\font-col.lua
tex\context\base\font-ctx.lua
tex\context\base\font-ext.lua
tex\context\base\font-gds.mkiv
tex\context\base\font-run.mkiv
tex\context\base\font-tra.mkiv
tex\context\base\font-unk.mkiv
tex\context\base\grph-fig.mkiv
tex\context\base\grph-inc.mkiv
tex\context\base\grph-trf.mkiv
tex\context\base\lang-def.mkiv
tex\context\base\lpdf-ano.lua
tex\context\base\luat-mac.lua
tex\context\base\lxml-tex.lua
tex\context\base\math-ali.mkiv
tex\context\base\math-ini.mkiv
tex\context\base\meta-ini.mkiv
tex\context\base\meta-pag.mkiv
tex\context\base\meta-tex.mkiv
tex\context\base\mult-aux.mkiv
tex\context\base\mult-dim.mkvi
tex\context\base\mult-ini.mkiv
tex\context\base\mult-low.lua
tex\context\base\mult-sys.mkiv
tex\context\base\pack-box.mkiv
tex\context\base\pack-mrl.mkiv
tex\context\base\pack-obj.mkiv
tex\context\base\pack-rul.mkiv
tex\context\base\page-brk.mkiv
tex\context\base\page-imp.mkiv
tex\context\base\page-ini.mkiv
tex\context\base\page-lay.mkiv
tex\context\base\page-mul.mkiv
tex\context\base\page-run.mkiv
tex\context\base\page-set.mkiv
tex\context\base\page-sid.mkiv
tex\context\base\page-txt.mkvi
tex\context\base\prop-ini.mkiv
tex\context\base\s-map-10.mkiv
tex\context\base\scrn-but.mkvi
tex\context\base\scrn-fld.lua
tex\context\base\scrp-ini.mkiv
tex\context\base\spac-ali.mkiv
tex\context\base\spac-def.mkiv
tex\context\base\spac-hor.mkiv
tex\context\base\spac-ver.lua
tex\context\base\spac-ver.mkiv
tex\context\base\status-files.pdf
tex\context\base\status-lua.pdf
tex\context\base\status-mkiv.lua
tex\context\base\status-mkiv.tex
tex\context\base\strc-des.mkiv
tex\context\base\strc-doc.mkiv
tex\context\base\strc-flt.mkvi
tex\context\base\strc-itm.mkvi
tex\context\base\strc-lst.mkiv
tex\context\base\strc-mat.mkiv
tex\context\base\strc-ref.lua
tex\context\base\strc-ref.mkvi
tex\context\base\strc-reg.mkiv
tex\context\base\strc-ren.mkiv
tex\context\base\strc-sec.mkiv
tex\context\base\supp-box.mkiv
tex\context\base\supp-num.mkiv
tex\context\base\symb-ini.mkiv
tex\context\base\syst-aux.mkiv
tex\context\base\syst-ini.mkiv
tex\context\base\tabl-tbl.mkiv
tex\context\base\tabl-xtb.mkvi
tex\context\base\type-set.mkiv
tex\context\base\type-siz.mkiv
tex\context\base\typo-cap.mkiv
tex\context\base\typo-cln.lua
tex\context\base\typo-cln.mkiv
tex\context\base\typo-krn.lua
tex\context\base\typo-krn.mkiv
tex\context\base\typo-spa.lua
tex\context\base\typo-spa.mkiv
tex\generic\context\luatex\luatex-fonts-merged.lua

The following were added:
metapost\context\base\mp-idea.mpiv
tex\context\base\font-col.mkvi
tex\context\base\font-emp.mkvi
tex\context\base\font-ini.mkvi
tex\context\base\font-pre.mkiv
tex\context\base\spac-lin.mkiv
tex\context\base\type-fbk.mkiv
tex\context\base\type-ini.mkvi
tex\context\bib\backup\sample.bib

And the following were removed (actually these are renames of some of the above files):

tex\context\base\font-col.mkiv
tex\context\base\font-ini.mkiv
tex\context\base\type-ini.mkiv

I've tried applying the changes individually but I ran into issues with things not being applied in the correct order. If anyone can suggest some files I should look at then I can experiment further.

Felix