Good evening TomĀ and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the issues you have been experiencing while trying to use our Pro add-on with Polylang. This was certainly not intended on our end.
As much as I hate being the bearer of bad news, the reason why you are experiencing such difficulties is because we officially do not support the Polylang plugin for multi-lingual websites. As you found out, it works quite well with our core free plugin, but things definitely get more complicated with all of our add-ons.
That being said we do support multilingual websites via WPML for both our free plugin and for our Pro add-on. Furthermore, we are looking at expanding WPML to cover all of our add-ons as part of our roadmap.
I wish I had a better answer for you, but for now it’s the best one I have.
The good news is your are fully entitled to a refund if you want one since you are within 30 days of your purchase. To obtain the refund, you just need to follow the procedure described here.
Best regards,
Geoff B.