Qualifications on title are very much at the discretion of the lender. If the issues that remain to be resolved are minor, they may let it go. They will be basing their decision on the underlying question - "if we have to repossess this house and sell it on, could this qualification make it harder for us to sell, or require us to do a lot of work to sort before it sells?" If yes, they're more likely to refuse agreement to proceed.
My experience is that it can take a long time for a lender's legal department to reply to such queries - think weeks or months. So I'd suggest that your solicitor writes to the lender's legal department immediately if not sooner and sets out the details of the proposed qualification.