ID1 form and the verifier's details acceptable to Land Registry

I am near exchange of contracts on the sale of a  flat and have reached a deadlock with one of the other shared Freeholders regarding their ID form in order to accomplish the transfer of deeds with HMLR. The solicitor who has verified the identity of the Freeholder on the ID1 form (and the Freeholder himself) strongly insist that as the verifier is an in-house solicitor (and personal contact of the Freeholder) and not completing the form on behalf or in the name of her employer, that she does not need to cite her employer's details on the ID1 but just her personal details - address, personal email & telephone number. She has only included her Roll number on the ID1 and this number refers to her employer on the Solicitor's Register but she refuses to authorise my solicitor to endorse these details on the form and insists she will only authorise her personal details to be used despite our reassurance that this is solely to verify her identity and her employer would not be under any liability in the proceedings. The solicitors on both sides of the house purchase will not accept the ID1 with the current details because as I understand it, without verification of her identity via employer's details HMLR will requisition the form even if the solicitors submitted it as is. I would be grateful if someone could confirm that this is the case in writing as this is now on course to obstruct the sale.

Lorraine - panel B of form ID1 sets out what details we require so I'm unsure as to what the issue is here. The verification must be by a conveyancer and PG 67 defines that role for you - Practice guide 67: evidence of identity - GOV.UK section 3
There's no requirement to name the firm who employs the conveyancer for example. If there is any issue with us being able to check and confirm that the verifier is a 'conveyancer' then we may raise a requisition but that all depends on the application as a whole inc how the form ID1 has been completed.

Many thanks for your prompt help. I think the problem is that the buyer's solicitor will not accept the ID1 as the verifier (who is an in-house solicitor has completed it ) citing experience of the slightest anomaly or omission of details on ID1s being requisitioned by HMLR so they are not even willing to attempt it. I have looked at the practice guide and it is a little difficult for a layperson to decipher. Can you confirm that an  in-house solicitor fulfills the criteria of a 'conveyancer'?

Lorraine - whilst I can appreciate the point the buyer's solicitor is making the definition is a clear one and the form equally clear. Whether they are 'in-house' or not is irrelevant here IF they are a solicitor/conveyancer that fits the definition.
But it's for the buyer's solicitor to decide what THEY will accept and why and if unwilling then it's an argument for them to resolve.
We won't consider the application and supporting evidence until it's submitted. Our guidance and forms are there to help them do that. I hope they can resolve the issue for you