HST not being applied to all products

[ Moderator note: moved to How-to and Troubleshooting. ]

I have a client site where we are using woocommerce for program registration (3, 6 and 1yr programs). I have setup hst taxes to be applied and see that they are added at checkout for the 6 month and 1 year programs, but is not being applied at checkout for the 3 month program. Do you know what could be causing the hst to not be applied to the 3 month program at checkout? How do I fix this?
https://www.tenyoga.ca/pricing/