Steps to reproduce:

1. Take any template f.ex. standard "Zabbix agent" template
2. Add new graph to it
3. Give name to graph
4. Select Graph type as Stacked
5. Add any item to it
6. Try to export the template and you will get error: Export failed - Invalid tag "type": unexpected constant value "1".

Result:
See screenshots

Notice that ZBX-27091 prevents you from seeing the error message
Expected:
Export of templates should work properly without errors