I'm using the PhoneTextBox from the Windows Phone Toolkit with InputScope="Text" to get autocorrect and text suggestions. While typing in the keyboard the text suggestions appears above the keyboard and I choose one of them. Immediately after the suggestion is taken the cursor of the TextBox resets to the start position. So if I continue typing then the new text is inserted at the beginning of the TextBox.
Here's an example: After choosing the text suggestion "Tests" the cursor begin of line.
EDIT: The issue is caused by an calling of BindingExpression.UpdateSource() within the TextChanged event handler. I can't find a workaround so I created an issue: https://phone.codeplex.com/workitem/11766