invariant_checker failure on a64: "Chunk instruction counts are inconsistent"

This happened a couple of times in both debug and release builds:

http://139.178.82.61:8080/job/DynamoRIO-AArch64-Precommit/2313/consoleFull

262:   *** postcmd failed (Child aborted): Trace invariant failure in T418399 at
262:   ref # 93263: Chunk instruction counts are inconsistent
262: 
262:   ***
262: 
262: Call Stack (most recent call first):
262:   /var/lib/jenkins/workspace/DynamoRIO-AArch64-Precommit/suite/tests/runmulti.cmake:120 (process_cmdline)
262: 
262: 
285/317 Test #262: code_api|tool.drcacheoff.invariant_checker ......................***Failed    1.08

Some later instances. They are always at ref 93263 it seems:

 Trace invariant failure in T498512 at
262:   ref # 93263: Chunk instruction counts are inconsistent

Trace invariant failure in T548743 at
259:   ref # 93263: Chunk instruction counts are inconsistent