You are experiencing the following issue
I have forked a collection from a Team Workspace to my personal workspace. When creating a pull request from a forked collection in a personal workspace, I see the error Reviewers can't access the source collection.
What to expect
- Any elements stored in a personal workspace are only visible to the owner of the workspace; other team members won't see them.
- To authorize a merge, the reviewers would need to be able to preview changes between both collections (the parent and the fork), so the forked collection has to be accessible by the team.
To be able to submit the pull request, move the collection from your personal workspace to a team workspace. The workspace does not have to be the same one where the parent collection is located; moving the collection to any team workspace will give reviewers the access needed.