The issue here is indeed that you have the wrong version of the Log4j dependency, it should be 2.6.2, not 2.7 for the 5.0.0 release. The other stuff about async and the LMAX disruptor is not the problem. This is the ideal option.
If for some reason this option is not available to you, you can also set the system property log4j2.is.webapp=true or log4j2.jmx.notify.async=false (either will be fine).