Tabindex not working consistently with combobox (one) and input text

Content

We have a page with several combobox (one) components and several input text components.  The tabindex has been defined on each component such that tabbing should take the user from a combobox to several input text boxes and back to another combobox.  However, if the user clicks on the first combobox and then tabs, the tab key takes the user through every combobox first before it takes them to any input text box.  However, if the user starts with an input text box, the tab key successfully takes through each component based on the correct tabindex value.