Field References Disappear

[srleeper]

Our office is currently running AutoCAD Map 2009.  About two years ago I spent the time to develop office standards for sheet sets and created callouts and title blocks using fields.  

For the most part it has been a good transition, however periodically when I open a sheet the field references in the blocks will have disappeared.  The blocks will hold the data from the last time they functioned, but the gray shadow box indicating the linked field is gone and it no longer updates when the sheet set properties are edited and fields are refreshed.  

It is easy enough to delete and replace a fresh block and all the fields will come in correctly; however I would like to get to the bottom of why this happens.  

Unfortunately there is no real pattern of why/when this happens that I have been able to decipher.  

Thanks,

Sarah

[АлексЮстасу]

Hi,

FIELDDISPLAY==1?

And it would be better to attach examples of such files / blocks.

[srleeper]

Unfortunately it is not that simple the field reference itself stops existing.

Attached ia an example problem drawing; there are three blocks in it all that were created with fields that reference sheet set properties.  One is holding it's field references (though it was replaced yesterday when it was not along with the title block which no longer is holding it's references) the other two are not and have also lost their names and have become a *Uxxx block.

I have attached the original blocks as well.