As you can see, builds 24 to 30 are for the same commit. #27 reports no warnings (not only the graph). The logs for each run are identical (except timestamps and such). The relevant lines are below the image, as well as the excerpt from the Jenkinsfile calling the reporter.

===> Compiling erlide_ide
_build/default/lib/erlide_ide/src/model/erlide_db.erl:24: Warning: type kind() is unused
_build/default/lib/erlide_ide/src/model/erlide_db.erl:100: Warning: function module_key/1 is unused
_build/default/lib/erlide_ide/src/model/erlide_db.erl:103: Warning: function module_props/2 is unused
 
step([$class: 'WarningsPublisher', canComputeNew: false, canResolveRelativePaths: true, canRunOnFailed: true,
consoleParsers: [[parserName: 'Erlang Compiler (erlc)'], [parserName: 'Maven']],
excludePattern: '', healthy: '', includePattern: '', messagesPattern: '', unHealthy: ''])
 

What are the [WARNINGS] messages in the console log for job 27?

Do you mean this? It is identical to the other jobs' (except for the reference build for deltas)

===> Compiling erlide_ide
_build/default/lib/erlide_ide/src/model/erlide_db.erl:24: Warning: type kind() is unused
_build/default/lib/erlide_ide/src/model/erlide_db.erl:100: Warning: function module_key/1 is unused
_build/default/lib/erlide_ide/src/model/erlide_db.erl:103: Warning: function module_props/2 is unused

[Pipeline] step
[WARNINGS] Parsing warnings in console log with parser Erlang Compiler (erlc)
[WARNINGS] Parsing warnings in console log with parser Maven
[WARNINGS] Computing warning deltas based on reference build #26
[Pipeline] step

Are the messages the same for the other builds? The warnings plugin should report a line that shows the actual number of warnings...

Maybe this is related to JENKINS-32191. Can you please add a sleep after your erlang build step?

Yep, a sleep seems to fix it, so I guess it's a duplicate of  JENKINS-32191. Thanks!

Oops, exactly when I said that I got a "no warnings" run... So a three seconds delay doesn't help.

Are the messages the same for the working builds? The warnings plugin should report a line that shows the actual number of warnings...

The logs are exactly the same. No summary (and I can't see one in other jobs either).

I think there was an issue on my side, it works now with the `sleep` workaround, so it is a duplicate of  JENKINS-32191. Thanks!

Ok, then please vote for the other issue to get it fixed as soon as possible