If you rebuilt and ran mvn -P cargo.run, conf/log4j2-dev.xml will be effective, not conf/log4j2-dist.xml.
In debug level logging, I thought you could have warnings (in debug level) from [1] and [2] in logs/hippo-site.log or command line console. But there might be other issues.
Are you using 12.x?
Woonsan
[1] https://code.onehippo.org/cms-community/hippo-site-toolkit/blob/hst-5.6.0/content-beans/src/main/java/org/hippoecm/hst/util/ObjectConverterUtils.java#L305
[2] https://code.onehippo.org/cms-community/hippo-site-toolkit/blob/hst-5.6.0/content-beans/src/main/java/org/hippoecm/hst/content/beans/manager/ObjectConverterImpl.java#L197