Custom taxonomies unchecked on plugin update

[WebworksJoe]

Can you reproduce this issue on default Wordpress theme (eg Storefront)?

Yes

Can you reproduce this issue when all other plugins are disabled except WooCommerce, Polylang and Hyyan WooCommerce Polylang Integration?

Yes

What product versions and settings are you using when this issue occurs?

• PHP: Tested 7.2 & 7.3
• WordPress: 5.2.2
• WooCommerce: 3.6.4 & 3.6.5
• Polylang: 2.6.0 & 2.6.1
• Hyyan WooCommerce Polylang Integration: Updating from 1.30 > 1.4.2 & 1.30 > 1.4.3 & 1.4.2 > 1.4.3
• Browser: Chrome 75.0.3770.100 (Official Build) (64-bit)

Steps to Reproduce

1. Set WC to display categories on shop page
2. Check front-end (only one language should display on /shop/ (different language categories on different shop page translations
3. Update Hyann from 1.3.0 to 1.4.2 or 1.4.3, or update from 1.4.2 to 1.4.3
4. Check front-end (all languages now shown on front-end shop page
5. Check PolyLang settings (Languages > Settings > Custom Post Types & Taxonomies). Product Categories, Tags and Shipping Classes are unset.

What I Expected

Product Taxonomies not to be unset on Hyyan plugin update

What Happened Instead

Product Taxonomies are unset on Hyyan plugin update

WordPress Environment

```

WordPress address (URL):		https://loadtec.webworksagency.co.uk
Site address (URL):		https://loadtec.webworksagency.co.uk
WooCommerce version:		3.6.5
Log directory writable:		/home/loadtecdev/public_html/wp-content/uploads/wc-logs/
WordPress version:		5.2.2
WordPress multisite:		–
WordPress memory limit:		512 MB
WordPress debug mode:		–
WordPress cron:
Language:		en_GB
External object cache:		–

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