It could be a database error, or is it possible it was a Show House on a new estate at some stage? That can cause this.
What do you mean by "missed out on a cabinet migration"? Were the lines previously fed directly from the exchange?
We could look a little deeper if you give the full postcode. With that we can compare all the properties on that postcode.
It is a database error - whoever wrote the Openreach reply had two choices
1. The line comes from a cabinet 2.5Km away. It is then routed 4.6Km in the wrong direction to a DP 7.1 Km away, before then having presumably a single cable 7.1KM long taking it to the house
2. The line is actually fed from the DP 0.0Km from the property and there is a mistake in the records.
I was enquiring as to whether a 7.1Km run from a DP was at all feasible. If it is then the choice to go for option 1 was merely from someone not engaging their brain, if it not then the choice was ridiculous.