I appreciate that you have let us know which theme you are using, as that is very helpful! Would you be able to share your online store URL? Also, did you happen to make any custom coding changes to the theme’s coding? As this will allow us to explore and take a further look into the issue occurring.
If you are not receiving any error messages when attempting to navigate to the checkout of the online store, I would suggest clearing the cache on your browser and try to navigate to the checkout again. If the issue persists, try this action on a separate browser - as for example, if you are using Safari, try this action on Google Chrome.
Let me know if that does the trick, looking forward to your response.