Why can’t I edit my variable products anymore?

Hello,

When we are trying to add variation to existing variable product (with cost of goods already entered) –
the page stuck and the product is not editable anymore and needs to be deleted
here is a error message I get from wordpress:

אירעה שגיאה מסוג E_ERROR בשורה 176 בקובץ /home/thethirdeyeco/public_html/wp-content/plugins/cost-of-goods-for-woocommerce/includes/class-alg-wc-cost-of-goods-core.php. הודעת שגיאה: Uncaught Error: Call to a member function get_parent_id() on bool in /home/thethirdeyeco/public_html/wp-content/plugins/cost-of-goods-for-woocommerce/includes/class-alg-wc-cost-of-goods-core.php:176
Stack trace:
#0 /home/thethirdeyeco/public_html/wp-content/plugins/cost-of-goods-for-woocommerce/includes/class-alg-wc-cost-of-goods-core.php(206): Alg_WC_Cost_of_Goods_Core->get_product_cost(10268)
#1 /home/thethirdeyeco/public_html/wp-content/plugins/cost-of-goods-for-woocommerce/includes/class-alg-wc-cost-of-goods-core.php(237): Alg_WC_Cost_of_Goods_Core->get_product_profit(10268)
#2 /home/thethirdeyeco/public_html/wp-content/plugins/cost-of-goods-for-woocommerce/includes/class-alg-wc-cost-of-goods-core.php(219): Alg_WC_Cost_of_Goods_Core->get_variable_product_html(2780, ‘profit’)
#3 /home/thethirdeyeco/public_html/wp-content/plugins/cost-of-goods-for-woocommerce/includes/class-alg-wc-cost-of-goods-core.php(270): Alg_WC_Cost_of_Goods_Core->get_product_profit_html(2780)
#4 /home/thethirdeyeco/public_html/wp-incl

Please help