A, B and D would be affecting on-site developers just as much as the remotes, but C (communication) is the thing that requires unique abilities for a remote worker.

If either the worker or the company is not good at communicating, that will cause serious problems. Poor communication from the managers can easily cause poor motivation and execution problems from the workers. If a worker is not communicating blocks or reaching out for the help they need, that can also lead to those problems.