Hi,
If I choose in QSO LIST window ->QSL->LOTW->Mark all QSO as uploaded to LoTW its changing LOTW QS_S for current date even for qsos which are already marked as sent to LOTW. IMHO it is not correct to change already exist LOTW QS_S and should work only for qsos which are not marked yet.
Otherwise, it leads to a situation where the LOTW confirmation receive date is earlier than the sent date, which is impossible with LOTW.
Did not check how it works with eQSL.

Slav, EI6KW