May be object property that TC is mapping is created crated dynamically eg. name = elementHost12 where 12 can be changed on run time. Or simply when TC looking for object it is not fully created and could not recognized.
Anyway letting TC to AutoMap object is not a good practice. You will end up with huge amount of unwanted object mapped and face wired situation such as this one.
so I recommend manually map objects what you really need. Specially once that are in top of object hierarchy and search most child objects using those mapped objects.
for this particular situation try manually mapping the object using unique properties.
you can read more in here
