Lately, I have seen a lot of people worrying about coastline edits "not showing up on the map."
Both the "admin" account and my personal account see a few messages every day, lately, asking "where are my coastline edits!?"
So rather than trying to keep answering those messages, I will post a reminder here.
The "render" - the program that makes what you edit show up on the map - is divided into parts. The "coastline render" is a separate part from other parts. As a result, if you make an edit involving the coastline - for example, you build a new little seaside town, on some new islands - the result can be temporarily strange, if the main render and the coastline render run at different times. You will see your new island town, but sitting in the water, because the coastline hasn't rendered yet.
Recently, the coastline render has been very slow. This is due to the large amount of work the coastline program has to do, and admin's efforts to make the best use of limited server resources. As a result, the coastline update can take a long time - even several days. Once I waited a week for a coastline edit to show up on the main map.
Also, it can look strange, because each "zoom level" of the map might render at a different time. So you might see your new island at zoom 15, but not at zoom 14, etc., for a while. And it makes our continental "floods" (when someone breaks the coastline) weird (only flooded at some zoom levels, for example) and harder to fix (because the coastline render is delayed, so a "flood" might be the result of some mistake someone made many days ago).
All of this is nobody's fault - it's just the situation with the server, right now.
Please be patient.
Nothing is broken. As many of you have noticed, there is nothing actually missing or broken with your edits - your new coastline work will immediately show up in an edit window (iD, potlatch, JOSM) - because the edit window renders the data in "live time" rather than waiting for the server. The problem is just a delayed update of the main map on the server.