I make a copy of a folder that has some jobs in it using "new item" --> "copy from"...
When opening the newly created folder, it is not possible to run any of the jobs because the "build" or "build with parameters" button is missing.
The workaround it to restart Jenkins and then the build hyperlink appears.
Thank you
Newly created jobs need to be explicitly saved once before they can be built. This is deliberate.
Whether the Folders Plugin does what would be expected by not doing this after a folder is copied is another question, but this is not a bug in core.