I made some Guild Islands with some alts to have access to the crafting stations with bonuses in each city. Then I went to bringing them from Custom setting to Public so everyone can visit it if they wanted. However it currently tells even the GM character of that guild that they don't have permission to change the perm setting away from Custom, not to Public, Private, or even back to Guild which it started on. I can still change all the settings under Custom and even have tried clearing them out but nothing lets me get it away from Custom. Also moving the Everyone listing from Uncategorized to Visitor doesn't work either.
Also have just checked this with my personal island. Once it is on Custom you can NOT change it back to Private. This seems to be a bad bug if you can't make an island Private or Public and only have the option of Custom.
the only access option for islands is currently "Custom". We are aware of the confusion showing the other unusable options causes and should change with an upcoming patch.
The reason for this is that you can't make it Public, otherwise everybody would have access to it. If you want to set it to Guild, you can just add your guild to one of the access rights.