Hi,
Had to run for lunch, but fixed it just before leaving. The problem was with the service connection that was using http address. Some months ago we switched to https and enabled http to https rewrite/redirection. Once i changed to https address the PR / Branch analysis started to work.
Odd that the usual master branch analysis doesnt bring this issue out, but good hunch Mickaël Caro, i also started to believe its related to the url rewrite from http to https, cant think of any other thing causing such behavior.
My first guess will be that characteristic value can contains an equal sign, which is the basic separator or key/values in query string, so that should be something like that, not 100% sure though.
i am also facing the same issue, since i am using aws ec2 for jenkins and sonar, since i am able to genrate post the report from jenkins command mode, but the same is not working when run it on jenkins pipeline.