After 1 month with no news, and after talking with peers and reading the reports on sites like this one, I decided to ask Plos One for news and specifically to ask how many reviewers had accepted to review. To my surprise, I learnt that zero reviewers had been secured, which in 15 years of being active has never happened, including twice at Plos One.
The editor was kept anonymous and the date of the last attempt to secure reviewers was unknown. So I decided that I was better off submitting elsewhere. I suspect that potential reviewers (including myself) do not see the interest of reviewing for this journal anymore, but that academic editors still accept the role but not the workload anymore.
Here is the semi-automatic response I got (same one as reported by others on this site)
"Thank you for following up. The Academic Editor assigned to your manuscript is unfortunately having trouble securing reviewers. This can sometimes happen if, for instance, the reviewers with the appropriate expertise are temporarily unavailable. However, we have reached out to the Academic Editor to help the peer review process proceed smoothly.
Please be assured that we are monitoring the progress of your manuscript and will be in touch again when the Editor has rendered a decision.
If there's anything else I can do to help in the meantime, don't hesitate to reach out. "
