HELP!!! Wall missing from Xref files until I click EDIT Xref in-place

[MatthewFortune]

I am working on a set of drawing drawn approx. 3 years ago by an employee that no longer exists at the firm.  This for the most part has the typical setup with a base file that is xref'ed into a sheet file.  The xref works just fine and appears as expected.  The sheet file on the other hand when I update the xref many or all of the walls vanish.  I have checked the display settings, made sure to copy the display style from the xref to the sheet file to ensure they match.  I have tried a few other things.  The only thing that seems to work is to edit the xref in place, then save it without making any chances.  At this point everything is fine even if I close the file and reopen it.  On the other hand if I open the xref and change something then save and close the Xref, return to my sheet file the walls vanish again.

I do not know what to do or what could be causing this.  I feel some weird or simple command is set wrong.

I will also add there are some unusual things with these file so I am starting to question if the former employee ran some weird commands.  One example is xref were coming in at different locations on different sheets.  Turns out the BASE command was 0,0,0 for some files and something else entirely for other.  PickFirst is not working as it should even with it set to 1.  Those are just examples of some unusual behavior with this file. 

If anyone has any suggestions please help. 

[MatthewFortune]

I will add this does not seem to be happening with additional files I am working with.  There are just 2 or 3 that this is happening but I can not figure out what is causing the issue.

[David_W_Koch · Accepted solution]

Good to hear that it is only happening with a few files.  Without seeing the files, it is hard to say what is going on.  I will say that I have found that I have found that in files with "poorly" modeled Walls (Walls slightly off, or not quite intersecting, or baselines not in the Z = 0 X-Y plane, etc.) that in the file itself, AutoCAD Architecture may be slightly more forgiving and manage to clean the Walls up anyway, but when externally referencing that file, the small errors are enough to cause cleanup issues.  Sometimes, running the OBJRELUPDATE command [on the View ribbon tab, on the Appearance panel, select the right side (downward pointing triangle) of the REGEN split button to deploy the menu and then choose Regenerate Model from the menu] and then pressing the ENTER key to regenerate the entire model will get things fixed. 

If not, then going into the source file and checking for "slightly off" Walls and then fixing them (or deleting and recreating them) may be necessary.  Set the UNITS Length type to Engineering and the precision to the maximum eight decimal places and you may find Walls with baselines tiny fractions of an inch above or below Z = 0, or, worse, Walls where the Baseline is not parallel to the X-Y plane (endpoints have different Z values).

Another possible issue would be if there were two or more instances of the external reference in the same place.  If Wall Cleanup between Host and External Reference is enabled, the Walls from each instance will try to cleanup with their counterparts in the other instance, creating cleanup errors that will make the Walls disappear.

[MatthewFortune · Accepted solution]

I think this might have just been one of those chases of CAD Gremlins.  The next day those files that were a problem the day before were working fine.