There is no issue. You just need to setup the field correctly. The size for a dropdown is in pixels so make sure it is large enough to hold your options. Then if you have values not showing, it would be due to incorrectly setup selection limits for your field values. Each value must have a selection limit given. If the dropdown has 3 values, then your selection limit would look like this:
0|0|0
0 represents unlimited. You can of course give an actual limit if needed. once a limit is reached, that value will no longer show.
This is all explained in the custom fields video tutorial. Thanks.