Select not working as expected in Search

Hi,

I have a grid application with a search function. The search function has several fields that use a select with an automatic lookup. Previously when a user searched, the select would be blank, and then when they commenced the search a list of applicable options would be presented, and when selected, tags would appear for the searched item(s).
search1

I do not know what has triggered it, but the latest compile changed the functionality. Now, when I go into search it lists all the data items in the box (of which there are several thousand). I can select, and multiselect items to search for, but I need to scroll down the entire list.

Search2

The above box lists all of the items, but I need to scroll down through it to find them.

Search3
Above is an item highlighted in blue, as it has been selected.

I do not know what has caused the change in behaviour. The odd thing is that when I launch the grid from within Scriptcase development it behaves as expected, but when loaded to my production server, it gives the second behaviour.

Any ideas of what I need to do in order to revert the behaviour to tag like selection?