For fuel request send it out as soon as you log in and it should work. Messages too. Can also test by just typing a period, if it doesn't work just try closing and reopening the app and trying immediately, it's annoying but has worked for me like that. Otherwise could be a device problem.
It’s been broken for me about half the time for months. It’s very inconsistent so I haven’t reported it. It’s just one more thing that makes this game less fun for me.