How to generate and auto increment Id with Entity Framework
This is a guess :)
Is it because the ID is a string? What happens if you change it to int?
I mean:
public int Id { get; set; }
You have a bad table design. You can't autoincrement a string, that doesn't make any sense. You have basically two options:
1.) change type of ID to int instead of string
2.) not recommended!!! - handle autoincrement by yourself. You first need to get the latest value from the database, parse it to the integer, increment it and attach it to the entity as a string again. VERY BAD idea
First option requires to change every table that has a reference to this table, BUT it's worth it.