I think I get the real issue, they claimed that the event had already started before you placed your bet, but I couldn't figure out everything clearly to verify their claim, they whole timezone differences is messing everything up, but reffering to the time on the shown to me on the bet slips you shared and in correlation to their calim are as follows:
The Event Started: 5 PM
Your bet was placed at: 5:46 PM
The Other person's bet was placed at : 5 PM
Upon checking the bestlip
https://nitrogensports.eu/betslip/665364eeFNZYUFxUklKbGhDanF3eVFKTGFDdz09/r/5147784/ again, the bet outcome has been settled (reversed) as canceled as well.
If indeed the event had started before your bet was placed, even without you knowing, then they have the right to cancel the bets.