Monty N
Slightly naive comment, as it is not just the technical members of the AAIB who determine when a report is released. I can think of delayed reports in the past where it has not been the AAIB or the investigation that were the problem, it was the lawyers for the party who appears to be "at fault" and thereby facing financial and reputational consequences, who then tried every avenue to "water down" the report findings before publication.
This particular airframe was one of the first in production, and it had reasonable use. One might therefore expect any issues in design, original build or maintenance scheduling to become apparent on an airframe like this. The information released so far indicates that a duplex bearing in the tail rotor control control mechanism failed and AW issued a service bulletin requiring this part to be checked in all 169 & 189 back in 2018. I guess that both AW and the AAIB know the result of that check, but to my knowledge that result has not been published. It would be interesting to hear from any owner or mechanic who can say what this check found.