You are using Select2 version 3, which is about 18 months out of date and contains known bugs, and is in turn, causing serious errors with WooCommerce Products, and preventing us from properly using WooCommerce.
This has been verified by Automattic, and you can read about the issue here:
https://wordpress.org/support/topic/3-0-error-option-ajax-is-not-allowed-for-select2/
I have reason to believe that your use of version 3 is causing additional problems with our site and additional plugins.
I urge you to update your files to use Select2 version 4. (I will be happy to forward you the technician’s reports from Automattic, if you like.)
Please advise, and fix.