Are you sure that DomainCatch and HostedChasing have caught none of your last 50 bookings? Were none of the domains auctioned on UKBackorder or DomainLore?
Did you manage to prebook all 50 names at the places that only allow 1 booking? For example it’s possible that some of the domains could have been caught on these tags and then automatically tag changed to their new owner before being checked on the Whois a few minutes later.