Starting a fastdebug Zero JVM with +XX:StartFlightRecording asserts with:
build/linux-x86_64-normal-zero-fastdebug/jdk/bin/java -XX:StartFlightRecording -version
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/os_linux.cpp:4076
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/disk/openjdk/upstream-sources/openjdk-hs/src/hotspot/os/linux/os_linux.cpp:4076), pid=425553, tid=425564
# assert(ms < 1000) failed: Un-interruptable sleep, short time use only
#
# JRE version: OpenJDK Runtime Environment (11.0) (fastdebug build 11-internal+0-adhoc.sgehwolf.openjdk-hs)
# Java VM: OpenJDK 64-Bit Zero VM (fastdebug 11-internal+0-adhoc.sgehwolf.openjdk-hs, interpreted mode, serial gc, linux-amd64)
# Core dump will be written. Default location: Core dumps may be processed with "/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %e" (or dumping to /disk/openjdk/upstream-sources/openjdk-hs/core.425553)
#
# An error report file with more information is saved as:
# /disk/openjdk/upstream-sources/openjdk-hs/hs_err_pid425553.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#
Current thread is 425564
Dumping core ...
Aborted (core dumped)

The crash originates from JFR code:

Thread 12 "java" hit Breakpoint 1, os::naked_short_sleep (ms=9223372036854775807) at /disk/openjdk/upstream-sources/openjdk-hs/src/hotspot/os/linux/os_linux.cpp:4076
4076 assert(ms < 1000, "Un-interruptable sleep, short time use only");
(gdb) bt
#0 os::naked_short_sleep (ms=9223372036854775807) at /disk/openjdk/upstream-sources/openjdk-hs/src/hotspot/os/linux/os_linux.cpp:4076
#1 0x00007ffff671222b in JfrThreadSampler::run (this=0x7ffff024a1e0) at /disk/openjdk/upstream-sources/openjdk-hs/src/hotspot/share/jfr/periodic/sampling/jfrThreadSampler.cpp:479
#2 0x00007ffff6a3c560 in thread_native_entry (thread=0x7ffff024a1e0) at /disk/openjdk/upstream-sources/openjdk-hs/src/hotspot/os/linux/os_linux.cpp:710
#3 0x00007ffff79a8564 in start_thread () from /lib64/libpthread.so.0
#4 0x00007ffff72c931f in clone () from /lib64/libc.so.6
(gdb) list
4071 // So calling this with 0 is an alternative.
4072 //
4073 void os::naked_short_sleep(jlong ms) {
4074 struct timespec req;
4075
4076 assert(ms < 1000, "Un-interruptable sleep, short time use only");
4077 req.tv_sec = 0;
4078 if (ms > 0) {
4079 req.tv_nsec = (ms % 1000) * 1000000;
4080 } else {
(gdb) p ms
$1 = 9223372036854775807

Until there is good support of Zero+JFR we should not build the feature by default.