Upgrade to 13 > development content not bootstrapped

Greetings,

We are currently upgrading from version 12 to 13.4.3-1. After completing all the steps from the upgrade guide, the development content that used to be there is not bootstrapped anymore. I could not find any info if something changed between the versions 12 and 13 regarding dev content.
This is basically what we have: there is a repository-data module with application and development module:

Basically only the config and content from the application module is initialized, but not the content from development hcm-content folder.

When trying to add new content through the CMS app, the autoexport module throws a NPE in > DefinitionMergeService:

protected ModuleImpl getModuleByAutoExportConfig(final JcrPath path) {
    // TODO extra logic from EventProcessor.getModuleForPath() and getModuleForNSPrefix()
    return moduleMappings.values().stream()
            .filter(mapping -> mapping.matchesPath(path))
            .map(mapping -> toExport.get(mapping.mvnPath))
            .findFirst().orElseGet(()->toExport.get(defaultModuleMapping.mvnPath));
}:

This is the stacktrace:

15:20:42 ERROR Processing events failed:
java.lang.NullPointerException: null
at java.util.Objects.requireNonNull(Objects.java:203) ~[?:1.8.0_202]
at java.util.Optional.(Optional.java:96) ~[?:1.8.0_202]
at java.util.Optional.of(Optional.java:108) ~[?:1.8.0_202]
at java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:193) ~[?:1.8.0_202]
at java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:190) ~[?:1.8.0_202]
at java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:152) ~[?:1.8.0_202]
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_202]
at java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:464) ~[?:1.8.0_202]
at org.onehippo.cm.engine.autoexport.DefinitionMergeService.getModuleByAutoExportConfig(DefinitionMergeService.java:1084) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.DefinitionMergeService.createNewContentSource(DefinitionMergeService.java:2185) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.DefinitionMergeService.mergeContentDefinitions(DefinitionMergeService.java:2048) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.DefinitionMergeService.mergeChangesToModules(DefinitionMergeService.java:273) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.EventJournalProcessor.exportChangesModule(EventJournalProcessor.java:590) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.EventJournalProcessor.processEvents(EventJournalProcessor.java:367) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.EventJournalProcessor.tryProcessEvents(EventJournalProcessor.java:254) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at org.onehippo.cm.engine.autoexport.EventJournalProcessor.lambda$new$0(EventJournalProcessor.java:128) ~[hippo-repository-engine-13.4.3.jar:13.4.3]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_202]
at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308) [?:1.8.0_202]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java) [?:1.8.0_202]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_202]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [?:1.8.0_202]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_202]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_202]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_202]

This is our autoexport-module.yaml:

definitions:
config:
/hippo:configuration/hippo:modules/autoexport:
/hippo:moduleconfig:
autoexport:modules: [‘repository-data/application:/’, ‘repository-data/development:/content’]

What I’ve noticed during debugging is that the “moduleMappings” contains both application and development modules, but in the end, only the application module is picked up, and the development module is not included in the baseline:

Unfortunately, from the official documentation I could not find what the problem could be, as I said until now everything worked fine, only with the version 13 it changed.

I tried out the sample project from the archetype, but unfortunately that one is set up for multi-site mode, and we would like to have only a single site.

Thank you!