Oreo introduced a new concept called Channel to the push notification. The fix is just to pass the target requirement but does not really address the requirement for Channel. Hence, it does not work. Please refer to this note, https://github.com/phonegap/phonegap-plugin-push/blob/master/docs/PAYLOAD.md#notification-channels
I had managed to fix it by downloading the git,modified the source code, gradle and plugin.xml and import the plugin resource file and then modifying the extensibility configuration to reference it to the plugin resource fileYou can download my unofficial update I had completed
EDIT:Applied the fix to Outsystem 10 file version as when I experimented the fix I am on Outsystem 11
This are the zip file containing modified source codes,the author can take a look