Steps to reproduce:

1. Open attached project
2. Open scene "repro"
3. Open script "test.cs"
4. Notice that it sets text value to string containing letters
5. Select InputField and notice that its Content Type is "Pin"
6. Run the scene and notice that value is successfully set to string seen in "test.cs"

Note: InputFields that have property Read Only enabled can also have their value changed through script.