Product category page not cached anymore

I have just updated to Woocommerce version 3.1.1. (from 3.0.7). I am using the KeyCdn cache enabler plugin for caching. Since the update the main product category page on the site https://www.4qd.co.uk/product-category/controllers/ is not being cached. It seems to have a nocache header, as cloudflare will also not cache the page. The other product category pages e.g. https://www.4qd.co.uk/product-category/accessories/ are still being cached ok. Has there been a change to the Woocommerce pages designated as DONOTCACHEPAGE ?

Woocommerce status report:

### WordPress Environment ###

Home URL: https://www.4qd.co.uk
Site URL: https://www.4qd.co.uk
WC Version: 3.1.1
Log Directory Writable: ?
WP Version: 4.8
WP Multisite: –
WP Memory Limit: 768 MB
WP Debug Mode: –
WP Cron: ?
Language: en_GB

### Server Environment ###

Server Info: Apache
PHP Version: 7.0.21
PHP Post Max Size: 128 MB
PHP Time Limit: 0
PHP Max Input Vars: 3000
cURL Version: 7.53.0
OpenSSL/1.0.2k

SUHOSIN Installed: –
MySQL Version: 5.6.36
Max Upload Size: 128 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

### Database ###

WC Database Version: 3.1.1
WC Database Prefix: wp_
woocommerce_sessions: ?
woocommerce_api_keys: ?
woocommerce_attribute_taxonomies: ?
woocommerce_downloadable_product_permissions: ?
woocommerce_order_items: ?
woocommerce_order_itemmeta: ?
woocommerce_tax_rates: ?
woocommerce_tax_rate_locations: ?
woocommerce_shipping_zones: ?
woocommerce_shipping_zone_locations: ?
woocommerce_shipping_zone_methods: ?
woocommerce_payment_tokens: ?
woocommerce_payment_tokenmeta: ?
MaxMind GeoIP Database: ?

### Security ###

Secure connection (HTTPS): ?Your store is not using HTTPS. Learn more about HTTPS and SSL Certificates.
Hide errors from visitors: ?

### Active Plugins (36) ###

LayerSlider WP: by Kreatura Media – 6.5.5
Advanced Custom Fields: by Elliot Condon – 4.4.11
Akismet Anti-Spam: by Automattic – 3.3.3
B09 Link to Existing Content: by BASICS09 – 2.2
BackupBuddy: by iThemes – 8.0.1.3
Black Studio Touch Dropdown Menu: by Black Studio – 1.0.0
Cache Enabler: by KeyCDN – 1.2.2
Enable Media Replace: by M?ns Jonasson – 3.0.6
EWWW Image Optimizer: by Shane Bishop – 3.5.0
Favicon by RealFaviconGenerator: by Philippe Bernard – 1.3.10
Heartbeat Control: by Jeff Matson – 1.0.3
PayPal for WooCommerce: by Angell EYE – 1.4.5.1
PW WooCommerce Bulk Edit: by Pimwick
LLC – 2.25

Q and A Focus Plus FAQ: by Lanexatek Creations – 1.3.9.7
Responsive Gallery Grid: by Jules Colle
BDWM – 2.0.5

Search & Replace: by Inpsyde GmbH – 3.1.2
Search By SKU - for Woocommerce: by Matthew Lawson – 0.6.1
Fast Secure Contact Form: by fastsecure – 4.0.52
Simple History: by P?r Thernstr?m – 2.17
Doc It: by SlickRemix – 1.1.7
WooCommerce Table Rate Shipping by Mangohour: by mangohour – 1.2.1
Testimonial Basics: by Kevin Archibald – 4.3.2
TinyMCE Advanced: by Andrew Ozz – 4.6.3
TinyMCE Spellcheck: by Matthew Muro – 1.3
Advanced Order Export For WooCommerce: by AlgolPlus – 1.4.2
WooCommerce Bulk Discount: by Rene Puchinger – 2.4.5
WooCommerce Display Products by Tags: by Sebs Studio – 1.0.0
WooCommerce WorldPay Gateway: by Add On Enterprises (Andrew Benbow) – 3.6.0
WooCommerce Product Gift Wrap: by Mike Jolley – 1.1.0
WooCommerce: by Automattic – 3.1.1
Yoast SEO: by Team Yoast – 5.0.2
WP Glossary: by TCBarrett – 3.1.2
WP Responsive Menu: by MagniGenie – 2.0.7
WP-Sweep: by Lester 'GaMerZ' Chan – 1.0.10
WPS Hide Login: by Remy Perona for WPServeur – 1.1.7
Custom Product Tabs for WooCommerce: by YIKES
Inc – 1.5.15

### Settings ###

API Enabled: ?
Force SSL: –
Currency: GBP (￡)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2
Taxonomies: Product Types: external (external)
grouped (grouped)
simple (simple)
variable (variable)

Taxonomies: Product Visibility: exclude-from-catalog (exclude-from-catalog)
exclude-from-search (exclude-from-search)
featured (featured)
outofstock (outofstock)
rated-1 (rated-1)
rated-2 (rated-2)
rated-3 (rated-3)
rated-4 (rated-4)
rated-5 (rated-5)

### WC Pages ###

Shop base: #4 - /shop/
Basket: #5 - /cart/
Checkout: #6 - /checkout/
My account: #7 - /my-account/

### Theme ###

Name: Fourqd Child Theme
Version: 1.2
Author URL: 
Child Theme: ?
Parent Theme Name: fourqd
Parent Theme Version: – 0 is available
Parent Theme Author URL: https://www.cambridgewebsolutions.co.uk
WooCommerce Support: ?

### Templates ###

Overrides: fourqd-child/woocommerce/emails/customer-on-hold-order.php
fourqd/woocommerce/emails/customer-processing-order.php