I used symbol with in libraries and that layer is alternated by symbolMaster, and if that layer has child what is expotable, I use sketchtool for exporting images. but, even has exportable layers. It doesn't export images.
I knew new things, that problem occurs because of foreign symbols. foreign symbols can't not exported by sketch tool,
please help, How do i to do export foreign symbols
Quick option is to open Sketch app, and convert items to vectors (outline)