First, my $ZVERSION:

Cache for OpenVMS/ALPHA V7.x (Alpha) 2010.1.6 (Build 952_2 + Adhoc 17754) 3-JAN-2018 14:32:54.07

Second, my issue:

I believe my current villain is “incremental compiling.” I was able to compare early compile output with later compile output:

Compilation started on 04/10/2019 10:46:32 with qualifiers 'cuk'
Compiling class UnitTests.Task3496 incremental compile detected
Compiling routine UnitTests.Task3496.2
Compilation finished successfully in 0.800s.