If you want to use Entity Framework you should start from scratch, don't use anything from mojoPortal.Data.EF.MSSQL, that was just some code I was experimenting with last February, it is not working code intended for anyone to use.
Actually I thought you wanted to use EF for your own custom feature development, you should be able to do that but mojoPortal is not currently supporting EF for core features.
Best,
Joe