Sharepoint "access denied..." when executing executequery after load fillversioncollection

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SharePoint

Hello folks, at my wits end on this one.

Receiving "Access denied. You do not have permission to perform this action or access this resource." error but only when attempting to acquire FileVersionCollection. Works fine if I omit the oclientContext.Load(fileversions).

Why would credentials work for the file, but not when loading the FileVersionCollection?

What I have tried:

Using oclientContext As ClientContext = New ClientContext("<sharepointsite>")
            Dim f As Microsoft.SharePoint.Client.File
            Dim fileversions As FileVersionCollection

            Try
                f = oclientContext.Web.GetFileByServerRelativeUrl("/" + e.CommandArgument.ToString())
                fileversions = f.Versions
                oclientContext.Load(f)
                oclientContext.Load(fileversions) //Works fine if I omit this
                oclientContext.ExecuteQuery()

            Catch sp_ex As Microsoft.SharePoint.Client.ServerException
                Context.Response.ContentType = "text/plain"
                If sp_ex.ServerErrorTypeName = "System.IO.FileNotFoundException" Then
                    f = Nothing
                    Context.Response.Write("File Not Found")
                Else
                    Context.Response.Write(sp_ex.ServerErrorTypeName)
                End If
                Exit Sub

            Catch ex As Exception
                f = Nothing
                Context.Response.ContentType = "text/plain"
                Context.Response.Write(ex.InnerException.Message)
                Exit Sub

            End Try

        End Using