Tax classes buggy on variable products

Since updating WooCommerce we’ve had some persistent bugs with applying tax classes to our variable products. We have taxes enabled. And we’ve set the default customer location to the Shop Base Address and have set the calculation of tax based on the Shop Base Address. We’ve always used tax classes to assign all taxes on a per product basis (our products are events that happen in different tax jurisdictions). However, the Standard Tax Rate seems to be overriding our other tax rates now.

Funnily enough, the correct tax rate gets applied to a few products! We can’t tell why it works sometimes, and not others. So, for example, we can’t get the HST tax rate to apply to Toronto (https://shop.eitrainingcompany.com/product/eq-certification-toronto/) but we can get it to apply to Ottawa (https://shop.eitrainingcompany.com/product/eq-certification-ottawa/). Many of our products use the Standard Rate and that seems to work fine.

We’re using Storefront and we’ve tried turning off all of our plugins. And everything looks good in our System Status.

Any help or insights to this quandary would be very much appreciated!