I observe a crash in JVMTI heap-walk code when running Shenandoah even with -UCOH:

make run-test TEST=serviceability/jvmti/Heap/IterateHeapWithEscapeAnalysisEnabled.java TEST_VM_OPTS="-XX:+UseShenandoahGC"

# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home/rkennke/src/openjdk/lilliput-jdk17u/src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp:180), pid=19088, tid=19095
# Error: Shenandoah assert_correct failed; Forwardee must point to a heap address

Referenced from:
  interior location: 0x00007f7828c280fb
  outside of Java heap
  0x00007f7828c280fb is at entry_point+155 in (nmethod*)0x00007f7828c27e90

Object:
  0x00000000f00015b0 - klass 0x00000008000018c8 java.lang.Class
    not allocated after mark start
    not after update watermark
        marked strong
    not marked weak
    not in collection set
  mark: marked(0x000000251a69d703)
  region: | 0|R |BTE f0000000, f0040000, f0040000|TAMS f0040000|UWM f0040000|U 256K|T 256K|G 0B|S 0B|L 238K|CP 0

Forwardee:
  0x000000251a69d700 - safe print, no details

See attached hs_err for more details.