I have a similar problem myself.
I have two fields on top of each other.
The first is "invisible" and lets me choose names from a dwindling list (ID numbers are stored)
The second field is just a calculation field that shows the full name from the ID number i just choosed. It looks like i choose names but instead ID.
Anyway; the dwinling list works excellent when i choose in browse mode but is empty in find mode.
I solved it in the script by adding this in the beginning:
If [ Get (WindowMode ) = 1]
Go to field [ your field ]
The Get(windowmode) returns the value 1 if it is in "Find" mode, then it simply sets focus on the same field that runs the script and then halts the script making it easy to enter values and press enter.
I have no idea what that script does or why it doesn't work in the first place - But it works and thats great!
Since there are no related records in "find-mode" the script does not know where to take you and simply stops ( i guess).
The focus stays out of the field you intend to fill in and the next time you klick it just repeats itself.
The small addition in the script simply checks if you are in "Find"-mode.
If this is true (1) the script sets focus on the field you just pressed and exits the script making it possible to use the field for searching.
got to love the get-functions!