At https://gitlab.com/groups/GROUPNAME/-/issues there used to be a way to pull a drop-down to choose a project to make a new issue. That seems to be gone now. It seems super tedious to go from that view to a place to add a new issue now. Why did this change?
Checking my own instance of gitlab-ce, I can actually do this. The option is still there. So I logged into gitlab.com to check, created myself a group, added a couple of projects, and yes, under the group issues there is no button.
You might want to open an issue here about it: Issues · GitLab.org / GitLab · GitLab so that one of the Gitlab devs can potentially fix it. Not sure why it’s missing from gitlab.com, and yet in a self-hosted it exists.