Maybe try the release candidate client. This client version is the one that starts a server on 8080, maybe that is causing some weird interaction. Don't know why it would be but, it might be worth a shot.
from log:
2021-03-14 16:49:21.806 INFO 2524 --- [JavaFX-Launcher] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''