Dunno how it got in there, but it sure is random.

you may have imported, as a prefab, and entity that you need to manually add to your .DEF list, like the flag pole spawn or the high back chair prop
Bah, stupid hosting, went away.
This map is supposed to BE a prefab, nothing imported into it. I only added the info_player_deathmatch and some light entities.
Open you .map in a text editor and make a search for “544” “-613” From what I can see in your pic above that key/value pair result should bring you to whatever is “UNKNOWN”. Dunno if it’ll help though.
I looked it up today, but when I loaded up my entities menu, it was gone. So strange… Radiant is starting to turn into a haunted house. Random things in random places that dissappear as fast as they appear.