Hello @Jimmmmmer,
Thanks for writing in and sorry to hear that you seem to be experiencing some issues. For a little more context on this situation, while our troubleshooting article references that v3.1.1 of WooCommerce is our “latest supported version” because that was the version that was out when our last major release came out around that time, it should be noted that our WooCommerce integration is highly superficial, meaning that we mostly integrate with it on a styling level and leave templating changes to a minimum. When X initially launched, we had a much more involved WooCommerce integration, but with the level of integration people want along with 3rd party plugins that often inject themselves into the mix, we have since moved to make things much more streamlined in this regard.
If you go to the WordPress admin at WooCommerce → Status → Templates (section at the bottom of the page) you will see that we have a very minimal number of templates we overwrite in the theme, and most of these updates are very minor. Also, any templates that are “out of date” will show up here, and you will see with WooCommerce v3.2.5 that none of them are, and none of the templates overwritten are in relationship to the checkout process.
It is more likely the case that something is going on with the overall setup of WooCommerce with your particular hosting environment, or perhaps with updating to the latest versions of WooCommerce, some of the database updates that they do regularly on update did not go quite right. This may be something that you wish to contact the WooCommerce team about, as they would have more information on that portion of the plugin (again, our integration is far from functional or having to do with overwriting large portions of functionality, it’s more akin to a coat of paint on a house than anything structural done).
The first thing I would do is check out that WooCommerce status page mentioned above, and see if there’s anything else going on there that indicates an issue with your environment. That might give you some clues of things to troubleshoot with your host that could be causing an issue, or are potentially not quite right with the overall setup of WooCommerce in your WordPress installation. If you still feel that there is something theme related after reviewing that information or if you are unable to get assistance from the WooCommerce team, you can let us know from there, but we would need your login information (in a secure note) to check things out first hand.