I have only been testing out trees and foliage on the map and have done only quick placement by copy paste.
+Edit
1000+ object manual placement test yield no corruption so far.
+Edit 2
There were corrupted ones in the manually placed group and copypasting revealed a spot on the map where a all placed objects appear to get stuck in a limbo.
Pictures attached:
1: shows the retangle of doom
2: shows how there are a few corrupt objects among normally working ones
+Edit 3
Further testing revealed that manual placing does indeed have same problem.
Picture 3 shows how there seems to be objects on the map, but library count says 0
+Edit 4
Pic 4:
Found another deadzone. All objects placed on the area are unresponsive.
+Edit 5
From a 1000 trees there were 17 bad ones that I started deleting one by one, some stuck on screen and some I were able to select and delete. After a few I noticed that selecting corrupt one and moving it seemed to fix it as moving an object seems to remove it from object list? So when it was moved it got re-entried on the list.
+Edit 6
Another group test showed that sometimes a corrupted object needs to be deleted multiple times before it disappears. Also when corrupted objects are stuck on the map TB crashes on exit (save works normally). After restart and reload the deleted objects are gone.
Map properties
Name: "MapFrame_1" [current]
Easting (m)..............: 500000.000
Northing (m).............: 7800000.000
Size (m).................: 20480.000 x 20480.000
Terrain grid size (cells): 4096 x 4096
Terrain cell size (m)....: 5.000
Imagery size (px)........: 8192 x 8192
Imagery resolution (m/px): 2.500
Texture layer size (m)...: 40.00 x 40.00