I think the issue here is a root cause problem with the 6.1.* express builds: they embed Tomcat 8 instead of Tomcat 9 (which even the 5.4.* express builds came with). That sure seems a mistake. Can anyone confirm if it’s somehow intentional? (I’m not raising a bug report, since I can’t know the answer. But I will note that the 6.0* Express versions I checked DID have Tomcat 9.)
And that Tomcat version downgrade would seem to complicate things like what you worked around while ALSO changing the Java version that it supports (which is as much about Tomcat as about Lucee itself).
Does anyone know who is responsible for the Express installer build? So that we can ensure to get their attention on this, if appropriate?