I have a created a Forms process that uses a drop-down field. This drop-down field is populated from a lookup rule and also has a static option. When you have this configuration, you are unable to select the "Assign values to choices" option and the "Append choices to lookup results" at the same time. The drop-down field populates correctly, and I can see the options from the database and the static option I added.

When the form is submitted though and the static option is selected, the variable value is showing as "Choice 1".

We are using Forms version 11.0.2311.50564.