EF Core blazor Error while SaveChangesAsync()

Error: System.InvalidOperationException: A second operation started on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext.

This happens if I do a custom filter/search on a RadzenDropDown field that is bound to a IQueryable list and then attempt to SaveChangesAsync(). It doesn't happen if I just pick an item from the RadzenDropDown list without filtering.