I cannot use empty text with single select value. When I select the value it overlaps the empty text. And another is when a value is selected and I type something on tagfield and then erase it the selected value still appears but it does not give any value when I get it through getValue(). Is there any solution or workaround for it? Here is the fiddle for single select tagfield.
The id: 0 troubles the combobox. Probably it confuses it with an empty selection. Use only ids > 0 for your records.