The icon that stores compasses until you have enough to expand has disappeared. How do you get it back?

I believe it means you have enough compasses but not enough stars. Press on next plot of uncovered land it will tell you how many compasses needed/number you have. It should also say how many stars are required. If you go to cash register on main page, upper right corner will tell you how many stars you currently have. You’re likely just short of the requirement of stars. Hope this helps.

The compass icon will no longer open up other islands

To see compasses collected, tap on a lightly clouded plot that is adjacent to open land. There you will see how many compasses you have and how many are needed for that plot. If you've cleared Orchid Island of clouds, then you'll have to go to the current island you are opening. There is no other icon that shows number of compasses. If you've caught up to developers and still have an excess of compasses, then contact customer support to ask them how many you have.