Sometimes when i take a "help X farmers" task and then actually try to fill boat crates, truck crates or help someone in their city, it wont work.

Most times it just turns Grey for a second or two and then it is available for filling again and sometimes i loose whatever items that was wanted but dont get Credit for it and it is still marked as an active helping option.

My wife has the same problem, so not a problem om just My Phone.