Oooo. It works!
After I adjusted the heapsize from default 512m to 4g for Logstash and Kibana, Logstash managed to process the split without the heapsize error:
split { field => "[reply][alerts]" }
From one record to more than 100 records now in Kibana. Then an error hits
handleSearchError@http://localhost:5601/55434/bundles/plugin/data/kibana/data.plugin.js:1:409692
search/</<@http://localhost:5601/55434/bundles/plugin/data/kibana/data.plugin.js:1:412433
a/</s<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:364:106267
t/s._error<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:6:29525
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
__kbnSharedDeps_npm__</c</t.prototype.error/<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:329:46099
o@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:252982
__kbnSharedDeps_npm__</c</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:329:45966
error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:430606
__kbnSharedDeps_npm__</m</e.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:89793
__kbnSharedDeps_npm__</f</t.prototype._error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:89350
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
o@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:364:254482
__kbnSharedDeps_npm__</l</e.prototype._trySubscribe@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:272:15794
__kbnSharedDeps_npm__</l</e.prototype.subscribe/<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:272:15716
o@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:252982
__kbnSharedDeps_npm__</l</e.prototype.subscribe@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:272:15631
a/</s<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:364:106309
t/s._error<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:6:29525
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
s/</<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:364:125124
t/s._error<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:6:29525
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
__kbnSharedDeps_npm__</f</t.prototype._error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:89350
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
s/</<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:364:125124
t/s._error<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:6:29525
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
__kbnSharedDeps_npm__</f</t.prototype._error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:89350
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
__kbnSharedDeps_npm__</f</t.prototype._error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:89350
__kbnSharedDeps_npm__</f</t.prototype.error@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:334:88987
v/</<@http://localhost:5601/55434/bundles/kbn-ui-shared-deps-npm/kbn-ui-shared-deps-npm.dll.js:272:7745
Another licensing error
[2022-10-21T01:45:35.849+00:00][WARN ][plugins.licensing] License information could not be obtained from Elasticsearch due to ConnectionError: getaddrinfo ENOTFOUND elasticsearch error
Troubleshooting in progress. Trying to poll the data in batches instead of "Everything"