Hello,
From what I understand, one or two weeks ago, the biber package (bibliography helper for LaTeX) got updated in Jessie to version 1.7. However, that version needs biblatex version > 2.5 and, with the latest upgrades, I only have version 1.7.
Since the update, biber issues a warning:
WARN - Warning: Found biblatex control file version 1.7, expected version 2.5
and compilation does not produce the citations.