Hard to say without seeing the capx, but here are a few guesses:
Run the game in debug mode. Select the object and view its values; you should be able to see a dotted red outline on the layout when the object is selected:
If it no longer exists in the object list then an action somewhere in your code is destroying it.
If the red outline appears in the correct position and at the correct size then most likely it has either been set invisible, the opacity has been set to zero, or some other object is obscuring it; you can check the relevant instance values to determine if it's one of these options.
If the object exists in the object list and the (x,y) coordinates are correct but no red outline is shown then either the object or the layer scale/size may be set to zero.
If it appears to have moved and the (x,y) coordinates have changed then an action somewhere in your code is re-positioning it before anchoring.
If it appears to have moved but its (x,y) coordinates stay the same then it may be that you have the origin set to different positions on subsequent frames (if the sprite is animated).