Try setting in a separate step

Author: GilbN

.github/workflows/docker-build.yml

@@ -43,11 +43,12 @@ jobs:
           echo "vendor=${{ github.repository_owner }}" >> $GITHUB_ENV
           echo "url=${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY,,}/blob/master/README.md" >> $GITHUB_ENV
           echo "VERSION=${{ github.event.release.tag_name }}" >> $GITHUB_ENV
-          echo "platform=$(echo $ARCHITECTURE | sed 's/-/\//g')" >> $GITHUB_ENV
           echo "cache=${GITHUB_REPOSITORY,,}:${{ github.ref_name }}-cache-${{ matrix.architecture }}${{ github.event.inputs.tag }}" >> $GITHUB_ENV
           echo "tag=${GITHUB_REPOSITORY,,}:${{ github.ref_name }}-${GITHUB_SHA:0:7}-${GITHUB_RUN_NUMBER}-${{ matrix.architecture }}${{ github.event.inputs.tag }}" >> $GITHUB_ENV
           echo "release=${{ github.event.release.target_commitish }}" >> $GITHUB_ENV
-
+      - name: Set platform
+        run: |
+          echo "platform=$(echo $ARCHITECTURE | sed 's/-/\//g')" >> $GITHUB_ENV
       - name: Set up QEMU
         uses: docker/[email protected]