ExcelFile.OptionsForceUseCheckCompatibility Property
When the option OptionsCheckCompatibility is true, Excel will refuse to austosave the file. To avoid a confusing situation where Excel refuses to autosave the file and shows a vague warning about an "older file format", OptionsCheckCompatibility is ignored by FlexCel.
In order to force FlexCel to save OptionsCheckCompatibility to the file (thus disabling the "Autosave" function) you need to set this property to true besides OptionsCheckCompatibility.
Syntax
Namespace: FlexCel.Core
public abstract Boolean OptionsForceUseCheckCompatibility { get; set; }