The runtime script may have an issue with max number of open files setting.
My system (MacOS) has the following system settings:
$ ulimit -H -n
unlimited
$ ulimit -S -n
256

run_windup.sh now sets the maximum number to 1024.

The first warning at startup now is:
16:08:12,388 WARN [org.jboss.as.warn.fd-limit] (main) WFLYSRV0071: The operating system has limited the number of open files to 1024 for this process; a value of at least 4096 is recommended

I believe RHAMT itself would need more than 1024 for large application portfolios/archives?

Solution: I increased the number in run_windup.sh to 10000.