The Pierre Auger and Telescope Array joint Working Group on the UHECR energy spectrum was established in 2012 to analyze energy scale uncertainties in both experiments and to investigate their systematic differences, particularly in the spectral shape of the flux measurements. Previous studies have indeed shown that, within systematic uncertainties, the energy spectra measured by the two observatories are consistent below $10\,\mathrm{EeV}$. However, at higher energies, a significant difference remains. In this work, we re-examine this discrepancy in greater detail and explore its possible origins. We consider systematic and statistical uncertainties, including the conversion from directly measured observables to energy and the calculation of exposures. We present an updated energy scale comparison between the two experiments and updated flux measurements in the common declination band.