Consider
@startuml
title something
|lane1|
|lane2|
|lane1|
'label label
'split
-[hidden]->
start
label space0
'end split
@enduml
//www.plantuml.com/plantuml/png/SoWkIImgAStDuIh9BCb9LIZEpqqjoSZCI-UgoKdCIpMiWT16DLnm0VMSnAJK70KmoQLUN92JMSAb6vsHcPAIcXUhQyS5Df4BegYu834vrO2BIpqrBqK1ejG1o0JQ1m00
Once the comments are removed from the label and the split commands, the arrow becomes unhidden.
//www.plantuml.com/plantuml/png/SoWkIImgAStDuIh9BCb9LIZEpqqjoSZCI-UgoKdCIpMiWT16DLnmWPp4fDGS1J39LLoGard2fHkTaPcIafeNgsl71JOFggQu834vrO2BApKlHG6YqW7815e60000