BB, we should be on the look out for a press release soon from AMRN regarding a formal PDUFA delay with explanation.
I don't think they will be putting out a press release based on the fact that it would not contain any new information from their 8 Aug 2019 press release (hyperlink) and they have already filed a Form 8-K on 12 Sep 2019 regarding the extension (see post #214911).
Every one of those delays was because enough new info was asked for and received that FDA considered it to be an amendment to the NDA or sNDA - if that's what happened to AMRN I believe they would have said it in their PR - I really don't think FDA has told them why they called for an AC so late and delayed the PDUFA by 3 months.