Thank you for your post.
Our Development and Testing departments are already aware of this issue with FileMaker Pro 14 under Windows. This issue was originally reported on the forum at:
I have attached your post to the original report. When more information becomes available, I will post again.
I prefer to use an auto-complete text field with a value list of just the customer name, but with a set up that uses the name to look up the ID number. This requires scripted support to handle cases where you have duplicate names or enter a name that does not match any record, but once all that is done, you have a much more user-friendly experience than just scrolling the value list by the first letter.
An example of this method can be found here:
+1000 to Phil's solution.
I have tested the same value list hiding the first field (Contact No.) and leaving just the second field visible (Customer Name) and it works.
This issue has been addressed in FileMaker Pro 15.