cpanm on debian 12 fails to install modules

We’ve seen cases where installing a perl module via cpanm fails silently to actually install the module. This is occurring on Debian 12.

For example:

cpanm --installdeps --notest Unicode::Lite

completes without error. But use of this module in a perl script fails due to it not being installed (in any of the standard system/library locations).

If we cd to the appropriate .cpanm directory and run

gmake

gmake install

the modules installs and is useable.

cpanm is executed as the root user. What are we missing?