WC External Variations: An error has occured, see console

hello,
this is a product with 38 variations and on clicking the buy button, im getting this error message: WC External Variations: An error has occured, see console

i am using this plugin so far for products with max 3 variations and it works. have updates htaccess data to:

php_value upload_max_filesize 256M
php_value post_max_size 2568M
php_value max_execution_time 600
php_value max_input_time 600
php_value max_input_vars 10000`
but no change.

in my console im getting the following errors:

TypeError: $.parseJSON(...).find is not a function
    <anonymous> https://moebel-guru.com/wp-content/plugins/wc-external-variations/assets/js/wcev_main.js:65
    jQuery 2
        dispatch
        handle
wcev_main.js:89:14
    <anonym> https://moebel-guru.com/wp-content/plugins/wc-external-variations/assets/js/wcev_main.js:89
    jQuery 2
        dispatch
        handle
TypeError: $.parseJSON(...).find is not a function
    <anonymous> https://moebel-guru.com/wp-content/plugins/wc-external-variations/assets/js/wcev_main.js:65
    jQuery 2
wcev_main.js:89:14
    <anonym> https://moebel-guru.com/wp-content/plugins/wc-external-variations/assets/js/wcev_main.js:89
    jQuery 2
TypeError: $.parseJSON(...).find is not a function
    <anonymous> https://moebel-guru.com/wp-content/plugins/wc-external-variations/assets/js/wcev_main.js:65
    jQuery 2
wcev_main.js:89:14
    <anonym> https://moebel-guru.com/wp-content/plugins/wc-external-variations/assets/js/wcev_main.js:89
    jQuery 2

?

can anyone help to solve this?

thank you
maria

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