Poor lighting
Not enough light or too much light with shiny specular highlights. Try and avoid environments with poor lighting.

Few contrasts
If you point your camera at a white wall there is really nothing unique to extract, ARKit won’t be able to find or track you. Try to avoid looking at areas of solid colors, shiny surfaces etc.

Fast movement
If you move the camera too fast you will end up with blurry images that will cause tracking to fail.

The best results are achieved when the world object is 10cm to 70cm away from your device. If the distance to the object is larger, it is advisable to measure on a detected surface.

Unfortunately, at the moment ARKit is not able to save the real world position of an object over the end of a session. We will update the app as soon as this is possible. Until then, make sure to create your object fully in one session and save it afterwards.