Thanks for responding.
I don't have a stacktrace, but if you could point me in the direction of some instructions to get you what you need I can try and get one for you.
I can't attach the jar file as it throws an error when I try an post the message. I've copied a file called logstash-logback-encoder.jar to the lib dir. The jar file contains other jar files (see list below), I've tried copying them into the lib dir separately as well as not putting them in there but it makes no difference. I've tried both v5.2 and 4.11 of logstash-logback-encoder.
commons-lang-2_6_jar_.jar
disruptor-3_4_2_jar_.jar
jackson-annotations-2_9_0_jar_.jar
jackson-core-2_9_6_jar_.jar
jackson-databind-2_9_6_jar_.jar
java-uuid-generator-3_1_5_jar_.jar
logback-access-1_2_3_jar_.jar
logback-classic-1_2_3_jar_.jar
slf4j-api-1_7_25_jar_.jar