  Intriguing results for tests of the universality of electrons and muons
through measurements of rates of $B\to K \ell^+ \ell^-$ and similar decays have
been in the spotlight for years. The LHCb collaboration has recently reported
new results which are in agreement with Lepton Flavour Universality, while the
individual decay rates are found below their Standard Model predictions. In
view of this new situation, we explore how much space is left for a violation
of electron-muon universality. Considering new sources of CP violation and
taking the new LHCb measurements into account, we show that significant
differences between the short-distance coefficients for electronic and muonic
final states are actually allowed by the current data. These patterns can be
revealed through CP asymmetries in neutral and charged $B\to K \ell^+ \ell^-$
decays. We obtain correlations between these observables and map them to the
short-distance coefficients. This results in regions in New Physics parameter
space with large differences between CP asymmetries of the decays with
final-state electrons and muons, thereby leaving a lot of room for possible
surprises in the future high-precision era.
