maybe a part of the whole image lies in UTM 50 but the part you are working on is no longer in it - consequently it cannot be displayed in that projection.
about resampling of S2, please read here: Resample processing time
maybe a part of the whole image lies in UTM 50 but the part you are working on is no longer in it - consequently it cannot be displayed in that projection.
about resampling of S2, please read here: Resample processing time