Can't convert pptx to pdf on some pptx file

I'm using Adobe.PDFServicesSDK 3.4.1 (C#) and got the following exception when trying to convert pptx to pdf

Error response received for the request: An error occurred while sending the request.   at Adobe.PDFServicesSDK.core.http.HttpClient.CreateHttpBaseResponse[T](RestResponse restResponse, HttpBaseRequest baseRequest)
   at Adobe.PDFServicesSDK.core.http.HttpClient.ExecuteRequestAsync[T](HttpBaseRequest baseRequest)
   at Adobe.PDFServicesSDK.core.storage.StorageAPI.<>c__DisplayClass0_0.<<CreateAssetUploadPreSignedURIs>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Adobe.PDFServicesSDK.core.storage.StorageAPI.CreateAssetUploadPreSignedURIs(InternalExecutionContext context, List`1 assetUploadURIRequests, String requestID)
   at Adobe.PDFServicesSDK.core.service.StorageService.UploadAssets(InternalExecutionContext context, List`1 sourceFileRefList, String requestID)
   at Adobe.PDFServicesSDK.core.service.CreatePDFService.ConvertToPDF(InternalExecutionContext context, FileRefImpl sourceFileRef, CreatePDFOptions createPdfOptions, String operation, String temporaryDestinationPath)
   at Adobe.PDFServicesSDK.pdfops.CreatePDFOperation.Execute(ExecutionContext context)