Odoo is the world's easiest all-in-one management software. It includes hundreds of business apps:
CRM | e-Commerce | Accounting | Inventory | PoS | Project management | MRP | etc.
The project_issue app has been removed in Odoo 11.
If you have an enterprise Odoo environment you can switch to the helpdesk module. This module has the ability to create tickets - which is almost identical to issues in Odoo 10:
If you really want it to be identical or are on the community version you could migrate the version 10 app to version 11. Alternatively, you could reach out to OCA about this at https://github.com/OCA to ask if they wish to migrate and support it.