Service will not start (RHE7)

Elastic Stack Elasticsearch
5

Further developments. I have stripped all the ES_TMP declarations and the JVM arguments are the same for both the service and direct. Directly it works with warnings, but the service fails with the following error:

java.lang.NoClassDefFoundError: Could not initialize class com.sun.jna.Native
        at org.elasticsearch.systemd.Libsystemd.lambda$static$0(Libsystemd.java:23) ~[?:?]
        at java.security.AccessController.doPrivileged(AccessController.java:312) ~[?:?]
        at org.elasticsearch.systemd.Libsystemd.<clinit>(Libsystemd.java:22) ~[?:?]
        at org.elasticsearch.systemd.SystemdPlugin.sd_notify(SystemdPlugin.java:115) ~[?:?]
        at org.elasticsearch.systemd.SystemdPlugin.onNodeStarted(SystemdPlugin.java:126) ~[?:?]
        at java.util.ArrayList.forEach(ArrayList.java:1511) ~[?:?]
        at org.elasticsearch.node.Node.start(Node.java:971) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.bootstrap.Bootstrap.start(Bootstrap.java:313) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:408) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:159) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:150) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:75) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:116) ~[elasticsearch-cli-7.14.0.jar:7.14.0]
        at org.elasticsearch.cli.Command.main(Command.java:79) ~[elasticsearch-cli-7.14.0.jar:7.14.0]
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:115) ~[elasticsearch-7.14.0.jar:7.14.0]
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:81) ~[elasticsearch-7.14.0.jar:7.14.0]

I can't understand with the same settings the service fails, but directly it will not.