What file did you open with the open tile?
type0.bmp (Atlas 0, Type 0) using Open Terrain Tile. The OE edit window remained blank (light blue) and title at top of window was [noname*][terrset00].
Tried type1.bmp and window remained blank.
Went back and tried type0.bmp with same results.
(I think I may have clicked Save and either nothing appeared to happen or the Open Tile window opened.)
Closed the OE, and shutdown the computer for lunch.
Restarted, opened the OE, and type0.bmp (red Atlas 0, Type 0) visible in window.
From here things are a little fuzzy.
Tried type1.bmp using Open Terrain Tile and window remained red Atlas 0, Type 0.
Tired type1.bmp using Open Object and window changed to blue Atlas 0, Type 1.
(Note: I had to change file type form Tiles(*.til) to All(*.*) and navigate to the texsrc folder to select bmp files.)
Back on track.
Re-opened type0.bmp using Open Object, added an object on the "T" in "Type 1" so I would know where it was, and hit Save with no indication the anything happened. (Object was CITYMISC/TOWNHOUSE1.srt.)
(Note: type0.bmp already had two objects on the tile but may have been inadvertently added while I was shifting the view with the A-key.)
Closed the OE and opened the TE. The added object was not visible until adding a check mark to Trees On.
Clicked Save, then Build, and closed the TE.
Started AH3, select the newly created terrain, and went Offline Practice.
Launched a P-51B and flew to open area that displayed "Atlas 0, Type 0" but object not visible. (Trees on other tile types are visible.)
Reset Graphic Settings to Default but no object visible.
Went to external view to remove any canopy effects and object was not visible.
Shutdown and restarted computer but object did not appear.