I can replicate it now, however it seems like a cache/compatibility issue as as soon as you refresh the page, the currency switches correctly. Therefore can you do the following: check if this issue appears in your test site when:
- Only WooCommerce and WooCommerce Multilingual plugins are activated, as it will tell us if there is an interaction issue with other plugin
- Theme is set to a WordPress default like Twenty Nineteen as it will tell us if there is an interaction issue with your theme
If you don’t see the issue happening in the above scenario, can you try to determine whether this is a theme or a plugin issue?
If you find a culprit, let me know so that we can test this in a minimal environment and escalate to compatibility team if required.