Restore your database from a backup (the old system) and run the following queries and ONLY the following queries on loot:
Code:
alter table loottable_entries add `droplimit` tinyint(2) unsigned NOT NULL default 0;
alter table loottable_entries add `mindrop` tinyint(2) unsigned NOT NULL default 0;
alter table lootdrop_entries change `chance` `chance` float not null default 1;
alter table lootdrop_entries add `multiplier` tinyint(2) unsigned NOT NULL default 1;
update loottable_entries set droplimit = 1 where probability != 100;
update loottable_entries set mindrop = multiplier, droplimit = multiplier, multiplier = 1 where probability = 100;
This will convert your tables to the new system, while keeping the old functionality. The problem was when I removed probability the conversion SQL was needed. Since it's added back, the only change needed is to set droplimit to 1 so that the tables will only drop 1 item at a time like in the old system. Multiplier ignores droplimit so that will still work as intended. Your chance and probability do not need to change at all (which is your issue in the example - your probability changed from 8% to 100%, but you didn't change chance to compensate.)
I'm going to go ahead and change the SQL on SVN to reflect this.