engineers without write access don't see see merge conflicts

All of our developers don’t have write permission on the repository. When a developer opens a pull-request, if there is a merge conflict it is not shown.
As an admin on the repo I had the expected message: “This pull request can't be merged. You will need to resolve conflicts to be able to merge. More information.”

If I grant write access on the repo to the dev it sees the message. I'll add that the dev can't see it on the main page but if he goes to the "diff" page he can see the conflict.