Autoconf, automake and stdcompat

I am trying to understand a series of build failures on the opam-repository ci involving stdcompat.12-18. It is clear that the build requires autoconf and automake, however, even adding the necessary dependencies, the build still fails with

#  cd . && /bin/bash /home/opam/.opam/4.13/.opam-switch/build/stdcompat.18/missing automake-1.15 --foreign
# /home/opam/.opam/4.13/.opam-switch/build/stdcompat.18/missing: line 81: automake-1.15: command not found
# WARNING: 'automake-1.15' is missing on your system.
#          You should only need it if you modified '' or
#          '' or m4 files included by ''.
#          The 'automake' program is part of the GNU Automake package:
#          <>
#          It also requires GNU Autoconf, GNU m4 and Perl in order to run:
#          <>
#          <>
#          <>
# make: *** [Makefile:895:] Error 1

on most distributions. In all cases I can see that automake 1.16 has been installed and from what I can see automake-1.15 is not hardcoded anywhere, so it must be generated during the configuration.

I have a mac and no docker, so I cannot reproduce the issue here. Does any of you know why this is happening?