In Office 365 I have created one custom list and in that created one Column as "Folder". When I have tried to access this field using RestAPI or CSOM or using U2U Caml query I am not able to get this fields information.
May be reserved name or reserved keyword I have also seen an internal name of this column is "Folder".
Not sure what is an issue with this column apart from other columns I am able to fetch information.
Also asked a question in SharePoint community as well. Reference link