Is there any evidence that the privilege holder has a voluntary intention to waive the privilege?

… Generally speaking, in cases where fairness has been invoked in support of a finding of waiver, there has been some manifestation by the privilege holder of a voluntary intention to waive the privilege, at least to some extent. In these circumstances, achievement of the principles of fairness and consistency may lead to a finding that the privilege has been waived in its entirety. The issue was helpfully canvassed by Holmes A.C.J. in United States v. Meng, 2020 BCSC 1461:

Implicit waiver may take place where a party does not expressly waive privilege, but takes a position in relation to privileged materials that is inconsistent with maintaining the privilege. This may be by, for example, selectively disclosing part of a privileged document or a category of privileged documents on a particular subject, but withholding the remainder of the document or other documents on that same subject. In these circumstances, to uphold the privilege over the remaining communications would be unfair, because the opposing party and the court would be deprived of access to the full narrative. In Huang v. Silvercorp Metals Inc., 2017 BCSC 795 at para. 143, Madam Justice Warren explained: The common thread in the cases where implied waiver is found is that the privilege holder has attempted to use and, at the same time, to shelter behind privileged documents. In such cases, fairness and consistency require production because the privilege holder uses the privilege as a sword to justify or explain a position or action while also using the privilege as a shield to prevent the other party from testing the justification or explanation.