Missing extensions after building Icecat 115.2.1

Add-ons Development
#1

Hi, I’m trying to build Gnu Icecat from Firefox sources version 115.2.1esr, but unfortunately only one of several extensions is present on the built binaries.

Could you please help me figuring out how extensions are backed into firefox when I build it from source tarball with ./mach build?

my extensions are first added to the manifest:
browser/installer/package-manifest.in

then copied over with:

cp "${DATADIR}"/extensions/ extensions/gnu -a

    cat << EOF >> browser/app/Makefile.in
libs::
	mkdir -p \$(DIST)/bin/browser/extensions
	cp -af \$(topsrcdir)/extensions/gnu/* \$(DIST)/bin/browser/extensions/
	mkdir -p \$(DIST)/icecat/browser/extensions
	cp -af \$(topsrcdir)/extensions/gnu/* \$(DIST)/icecat/browser/extensions/
EOF

Thanks in advance, any help is very much appreciated.
Chippy