So far as I am aware, these are all nonsense but are doing the rounds!
1) The road is too narrow for two lorries to pass.
2) Persimmon is holding WC to ransom and will not open the road unless they get planning permission for houses on the Gap.
3) The bat bridge is too low.
4) The electicity cables have not been buried deep enough.
5) The two roundabouts are too small.
6) The tarmac road surface is too thin.
7) The road has failed its 'Stage 3' safety inspection - actually, that one could be true.
There is a total lack of info from WC or anyone else on what is delaying the opening. I presume that Persimmon build their houses to a more reliable timetable than they seem to build roads!