Table edit and add working, list returns an error

Hello everyone

This is a bit of an odd error that I haven't seen before, although it's a fairly standard .NET Error.

This part of my .NET Runner application has always worked fine, I don't know why this error is now being returned.

Here is my database table, note that I can see that the database table hasn't changed in my version control:

In .NET Runner the Edit and Add view work fine, List view returns the following error:

Server Error in '/' Application.

Conversion failed when converting the nvarchar value 'Microsoft Trainingsgutscheine ' to data type int.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Data.SqlClient.SqlException: Conversion failed when converting the nvarchar value 'Microsoft Trainingsgutscheine ' to data type int.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SqlException (0x80131904): Conversion failed when converting the nvarchar value 'Microsoft Trainingsgutscheine ' to data type int.]

Note that there is an attempt to convert an nvarchar into an int, which seems a little odd.

This is what I've tried:

1. Resyncing the database
2. Removing the table and adding back in after rebuild
3. Removing List view and adding back in after rebuild

Any ideas would be appreciated.