epplus error on linked picture call from webapi - azure

Question

I have an issue with EPPLUS linked pictures.
My ExtJs website has a button that calls my Microsoft Azure webapi, and creates and downloads an excel file using EPPLUS. Everything works fine UNTIL I add a excel linked picture to the template I am using. (the template is saved on the Azure app service)
The weird thing is it works fine when the app service is run locally, but when I publish to Azure I get the error.
Here is the error...
System.Runtime.InteropServices.ExternalException (0x80004005): A generic error occurred in GDI+.
at System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams)
at System.Drawing.Image.Save(MemoryStream stream)
at System.Drawing.ImageConverter.ConvertTo(ITypeDescriptorContext context, CultureInfo culture, Object value, Type destinationType)
at OfficeOpenXml.Drawing.ExcelPicture..ctor(ExcelDrawings drawings, XmlNode node)
at OfficeOpenXml.Drawing.ExcelDrawing.GetDrawing(ExcelDrawings drawings, XmlNode node)
at OfficeOpenXml.Drawing.ExcelDrawings.AddDrawings()
at OfficeOpenXml.Drawing.ExcelDrawings..ctor(ExcelPackage xlPackage, ExcelWorksheet sheet)
at OfficeOpenXml.ExcelWorksheet.Save()
at OfficeOpenXml.ExcelWorkbook.Save()
at OfficeOpenXml.ExcelPackage.GetAsByteArray(Boolean save)
at xxxV003.Models.RepositoryExcel.ExcelSheet(FileInfo xlTemplate, String cName, String calcMethod, String username, Int32 cid)
at xxxV003.Models.RepositoryExcel.CreatePosSheet(String cName, String _calcMethod, String username, Int32 cid, HttpRequestMessage Request)
at lambda_method(Closure , Object , Object[] )
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.AuthenticationFilterResult.<ExecuteAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()