Column to predict dropdown is empty. Cannot select any column. Rest of page matches walkthrough

**System Information (please complete the following information):**
- Model Builder or CLI Version:
- Visual Studio Version (if applicable): 2023 17.6

**Describe the bug**
- On which page of the tutorial did you run into an issue (URL):https://dotnet.microsoft.com/en-us/learn/ml-dotnet/get-started-tutorial/data
- Clear description of the problem: "Column to predict" dropdown is empty. Cannot select any column. Rest of page matches walkthrough

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'Add step of wizard"
2. Browse to yelp_labelled.txt file
3. Data Preview is populated and columns col0 and col1 contain same data as the walkthrough shows
4. Open "Column to predict" dropdown.
5. Dropdown is empty

**Expected behavior**
Dropdown allows me to select col1

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Additional context**
Add any other context about the problem here.

Inizia riproducendo il problema nel Model Builder wizard usando yelp_labelled.txt del tutorial collegato, quindi esamina il passaggio Add del wizard flow e il popolamento del menu a discesa Column to predict. Verifica se col1 appare come colonna di destinazione disponibile e confronta il comportamento con l’anteprima dei dati prevista dal tutorial.

Scritto dal modello di indicizzazione a partire dal testo della issue.