>>You've been having some pretty strange problems, maybe you should call Panoramix or the Ghost Busters :-)
>
>I managed to get a workaround for this one. I can get the ReadOnly value from the Column instead.

This exact thing has happened to me also, as well as several other "default" properties in various objects have "slipped off" what they are supposed to be. You can try doing a right click on the property to reset to default, but it may slip off again. In this case, I just put hard code in some Method (like Init) to make sure the setting is correct. This is an odd bug, I hope it's corrected in future.