Plot split and registration

Hi
my son bought no60 at bd16 1sx in august 2023
The register still shows 56-64 as one unit.
my son has to relocate for work and has signed a contract on another house and has a buyer for 60
The conveyancer says the register status is causing a hold up and the worry is the buyer may pull out
We have no idea if there are queries outstanding or other issues, or just the result of a backlog
Could anyone please explain the problem?
can a sale go through for this transfer and it be added to the backlog, as must have happened in 2923

Hi David - No 60 was updated yesterday under title WYK619574. So hopefully whatever the problem was is now resolved
There had been a lengthy delay prior to that as another part of the 56-64 had been sold off and needed to be registered as well. 

Thank you