trying to open a job located in a folder from the classic view (open- blue ocean link) raises

a 404 error.  The URL in the link has correct escaping of slashes

Inspecting the http-requests seems to indicate that jenkins sends an intermediate page via Location:  that is not using https.

Initals request (https)

GET /jenkins/blue/organizations/jenkins/debocker%2FBuildEntangleContainersV2 HTTP/1.1
Host: <host>
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:65.0) Gecko/20100101 Firefox/65.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Referer: https://<host>/jenkins/job/debocker/job/BuildEntangleContainersV2/
Connection: keep-alive
Cookie: screenResolution=1920x1200; jenkins-timestamper-offset=-3600000; jenkins-timestamper=none; jenkins-timestamper-local=true; Upgrade-Insecure-Requests: 1

Response:

HTTP/1.1 302 Found
Date: Mon, 04 Mar 2019 15:43:13 GMT
Server: Jetty(9.4.z-SNAPSHOT)
X-Content-Type-Options: nosniff
X-Blueocean-Refresher: .....
Location: http://<host>/jenkins/blue/organizations/jenkins/debocker/BuildEntangleContainersV2/
Keep-Alive: timeout=5, max=86
Connection: Keep-Alive
Transfer-Encoding: chunked

Note the http in there.

Possibly also related to JENKINS-46347