Position Jump Bug
The page will explain what the Position Jump Bug is, and how to fix it.
If a player is meant to be in a different position than the one shown on screen then this is classed as a position tracker bug. In fact it is a group of bugs which can occur for several reasons.
A minor problem caused by this bug is that the player gets incorrect information about his ranking in the race. However an altogether more major issue is that the position tracker is the thing that determines which items should be granted to a player. Due to the face that the items selection is based on the shown position, the real leading player could have the opportunity to acquire more powerful items such as mushrooms which could then be used to dodge a blue shell unfairly - thus leading to poorly balanced racing where players in lower positions struggle to catch up to the leader.
That said, once people start crossing the finish line at the end of the race all positions are shown correctly again because the game compares the racing time of all players.
Temporary switching of positions
This kind of glitch mostly occurs if a player is outside of all valid check point quadrilaterals. If the player enters a valid quadrilateral again, the glitch is gone. Likely it is a problem of old tracks, that used the old check point line model to define the check points.
Incorrect positions after respawning
This is another version of a temporary positioning bug. The cause is quite simple: a respawn point is set so that when a player uses it they are placed after one of the mandatory checkpoints, therefore players will pass them in the wrong order and the game will get confused and provide the wrong position information. Occasionally this bug results in a lap not counting and obviously this can lead to a huge disadvantage to anyone unfortunate enough to fall victim to it.
Missing a mandatory checkpoint
Sometimes a player drives a little outside of a mandatory checkpoint line, resulting in a failed lap count. When this happens the position tracker of the aforementioned player will often be shown as last place, but should correct itself after a while.
Because of the simulation of other drivers until the next data transfer, other Wiis do not notice that the player has missed the checkpoint and will count them as being on another position.
All players at position 1
Some custom tracks are too long for the 5 minutes limit if playing online. One trick commonly used to overcome this is to set more than 1 lap counting check point. This works offline fine, but online each player is permanently registered as first after crossing the first lap counting check point.
If the real first place player finishes the race then all other players are registered as being in second place until the next player finishes, and so on.
Fixing The Bug
Fixing it is quite easy, and should be a pretty quick fix if done correctly.
In your course locate the areas in which this glitch takes place.
Once you have found each one, note down the area on the Minimap where it occurred.
Open your KMP file and then the "Checkpoints" section.
Now click a checkpoint that is placed slightly before the glitch occurs. Change the key setting to any number that follows up the previous key checkpoint.
Place more in the area ahead, and go in order of 1, to 2, to 3, and so on.
Do this step in every area that this happens, and in each section right before two paths cross over/under eachother.
Look through the rest of you courses checkpoints and make sure every single other key checkpoint that occurs after the new ones you added are one number above the one before it, so if the key checkpoint before it was 5, you would change it to 6.
Try your course in-game and see if this glitch still occurs. In the case that it does, repeat steps 1 and 2 until the glitch is gone.
Also read the next section to make sure that your course turns out okay after doing this.
Make sure that none of your respawn points try to drop you past a key checkpoint. This means that you fall down behind a point, and get respawned past it. If this happens, the lap will not count. There may be various ways to fix this depending on your course; you may have to change the model, move the checkpoint, or reset the respawn position.
Make sure that ALL key checkpoints go in numerical order. Failing to do so may also result in the lap not counting.