This is a personal experience rather than an authoritative answer, but I thought it would be relevant.
I fly a few airlines fairly frequently and have done for many years. I've always thought that blinds should be open for safety reasons. However, a few years back I was on a flight with an airline that I'd flown many times before and had always enforced the blinds-open policy. To my surprise everyone was asked to close the window blinds. Within a year the trend had increased to point where all flights by this airline were blinds-closed. Then, a year or so after that, the policy was reverted to blinds-open and has remained since.
My theory is that someone in the senior crew, or crew training, mixed up the policy and started enforcing the wrong one (i.e. blinds-closed). I think this is plausible as the reasons for having blinds-open are not entirely obvious. It would also explain the gradual adoption of the new policy. I guess someone eventually realised the mistake, hence the sudden reversal.
Sorry for the long post and lack of sources. Will delete if deemed not helpful.