Testing perch shop—empty cart after adding product to cart

Hi, I’m trying to set up a very simple implementation of perch shop on a standard perch site to sell just the one product. It’s the first time I’ve used perch shop and not got past basic testing of a product page with the simple add to cart form with:

<perch:form id="add_to_cart" app="perch_shop" action="/shop/cart">
  <perch:input id="product" type="hidden" value="<perch:shop id="productID" type="hidden" />" env-autofill="false" />
  <perch:input type="submit" value="Add to cart" />
</perch:form>

but the cart remains empty. Have tried without the env-autofill="false which doesn’t work either. And with the add to cart function directly from php product page:

<?php 
           perch_shop_product('my-product', [
            'template' => 'products/product_template.html',
           ]);
           perch_shop_add_to_cart('my-product');
?>

Debug message for the product page is:

SELECT * FROM perch2_pages WHERE pagePath='/buy/index.php' LIMIT 1
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[2] SELECT * FROM perch2_pages WHERE pageNew=0 AND pageHidden=0 ORDER BY pageTreePosition ASC
[1] SELECT pageTreePosition FROM perch2_pages WHERE pagePath='/buy/index.php' LIMIT 1
[1] SELECT pageID FROM perch2_pages WHERE pageTreePosition IN ('000-003', '000') ORDER BY pageTreePosition DESC
[2] Using template: /templates/navigation/navitem.html
[1] SELECT tbl.* FROM ( SELECT idx.itemID, main.*, idx2.indexValue as sortval FROM perch2_shop_index idx JOIN perch2_shop_products main ON idx.itemID=main.productID AND idx.itemKey='productID' JOIN perch2_shop_index idx2 ON idx.itemID=idx2.itemID AND idx.itemKey='productID' AND idx2.indexKey='_id' WHERE 1=1 AND ((idx.indexKey='slug' AND idx.indexValue='modelling-on-the-stand-for-intimate-apparel-jmee2')) AND idx.itemID=idx2.itemID AND idx.itemKey=idx2.itemKey ) as tbl WHERE (productDeleted IS NULL AND productStatus=1 AND parentID IS NULL) GROUP BY itemID, sortval ORDER BY sortval ASC
[24] SELECT DISTINCT settingID, settingValue FROM perch2_settings WHERE userID=0
[1] Using template: /templates/shop/products/product_template.html
[1] SELECT * FROM perch2_shop_currencies WHERE currencyID=47 LIMIT 1
[1] SELECT itemID, itemQty FROM perch2_shop_cart_items WHERE cartID=21 AND productID=0
[1] SELECT * FROM perch2_shop_products WHERE productID=0 AND productDeleted IS NULL LIMIT 1
Limiting based on stock.
------------------------------ Calculating cart ------------------------------
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[1] SELECT * FROM perch2_shop_tax_locations WHERE locationID=1 AND locationDeleted IS NULL LIMIT 1
[1] SELECT locationID FROM perch2_shop_tax_locations WHERE locationIsHome=1 LIMIT 1
[1] SELECT * FROM perch2_shop_tax_locations WHERE locationID=1 AND locationDeleted IS NULL LIMIT 1
[1] SELECT * FROM perch2_shop_currencies WHERE currencyID=47 LIMIT 1
[1] SELECT COUNT(productID) AS product_count, SUM(itemQty) AS item_count FROM perch2_shop_cart_items WHERE cartID=21
Tax mode: inc
[nil] SELECT * FROM perch2_shop_cart_items WHERE cartID=21 ORDER BY itemID ASC
UPDATE perch2_shop_cart SET cartTotalItems=NULL, cartTotalProducts='0', cartTotalWithTax='0.00', cartTotalWithoutTax='0.00' WHERE cartID='21'

and from the cart page:

 SELECT * FROM perch2_pages WHERE pagePath='/shop/cart/index.php' LIMIT 1
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[2] SELECT * FROM perch2_pages WHERE pageNew=0 AND pageHidden=0 ORDER BY pageTreePosition ASC
[0] SELECT pageTreePosition FROM perch2_pages WHERE pagePath='/shop/cart/index.php' LIMIT 1
[2] Using template: /templates/navigation/navitem.html
------------------------------ Calculating cart ------------------------------
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[1] SELECT * FROM perch2_shop_cart WHERE cartID=21
[1] SELECT * FROM perch2_shop_tax_locations WHERE locationID=1 AND locationDeleted IS NULL LIMIT 1
[1] SELECT locationID FROM perch2_shop_tax_locations WHERE locationIsHome=1 LIMIT 1
[1] SELECT * FROM perch2_shop_tax_locations WHERE locationID=1 AND locationDeleted IS NULL LIMIT 1
[1] SELECT * FROM perch2_shop_currencies WHERE currencyID=47 LIMIT 1
[1] SELECT COUNT(productID) AS product_count, SUM(itemQty) AS item_count FROM perch2_shop_cart_items WHERE cartID=21
[24] SELECT DISTINCT settingID, settingValue FROM perch2_settings WHERE userID=0
Tax mode: inc
[nil] SELECT * FROM perch2_shop_cart_items WHERE cartID=21 ORDER BY itemID ASC
Using template: /templates/shop/cart/cart.html

Grateful if anyone can tell me where I’m going wrong. The product is in stock. Perch diagnostics:

    Perch: 2.8.34, PHP: 5.6.2, MySQL: 5.5.38, with PDO
    Server OS: Darwin, apache2handler
    Installed apps: content (2.8.34), assets (2.8.34), categories (2.8.34), perch_shop_orders (1.0.11), perch_shop_products (1.0.11), perch_shop (1.0.11), perch_members (1.5)
    App runtimes: <?php $apps_list = array( 'content', 'categories', 'perch_members', 'perch_shop', );
    PERCH_LOGINPATH: /perch
    PERCH_PATH: /Users/kirsten/Sites/janice/prototyping280117/site_proto_v1/perch
    PERCH_CORE: /Users/kirsten/Sites/janice/prototyping280117/site_proto_v1/perch/core
    PERCH_RESFILEPATH: /Users/kirsten/Sites/janice/prototyping280117/site_proto_v1/perch/resources
    Image manipulation: GD
    PHP limits: Max upload 32M, Max POST 32M, Memory: 128M, Total max file upload: 32M
    F1: 6a33f95eca3667f9e0c39bf5ca2980fe
    Resource folder writeable: Yes
    HTTP_HOST: localhost:8888
    DOCUMENT_ROOT: /Users/kirsten/Sites/janice/prototyping280117/site_proto_v1
    REQUEST_URI: /perch/core/settings/diagnostics/
    SCRIPT_NAME: /perch/core/settings/diagnostics/index.php