auto complete drop down not placing all values in HTML

I have an autocomplete drop down with 18,000 values. This used to work with no issue. Now the form will only display a few thousand items.

Please fix.

I cloned your form and initially, seems like not all the option are there. I tested and the drop down does not show all the options at the same time.

I also copied the values in a text editor and all the values that I search are in the drop down.

Could you provide us the name of the cities or the values that are not appearing in the drop down? 

We will be glad to take other look to your form.