Thanks for the heads-up Benny. What printer and what country? Did you try the uninstall/re-install routine yet?
I looked up the software package for the P800 on the Epson Canada website. To get to it, I had to specify an OS. So I selected OSX 10.12 - I believe that is Sierra. It then pulled up the download options, which have dates and code numbers. No explanations, no "ReadMe" file accompanying the downloads, so no RTF file accessible before you install anything that explicitly tells you what it contains and what OS versions are compatible with it. One must believe it is Sierra-capable because it was accessed from the 10.12 routing process. There's nothing here designed to give a user much insight or confirmation of and confidence in what they're doing.
But assuming you downloaded the correct version for the OS and you are encountering problems, it means either you made some mistake(s), or you are a victim of early adopter syndrome. Yet again, save for the possibility of pilot error, it could be that Epson and Apple are not yet sufficiently cohered on these updates, awaiting the early adopters to notify problems to them for further attention - i.e. customer-managed QA/QC on the cheap.
I'm waiting till at least January before I change anything, and then depending on the status of the general operating experience, I may upgrade.