I have added the code you requested in the wp-config file. The line did not exist before – I just added your recommended definition at the bottom of the file. We now have 3 clients with calendars using the API. We are not able to assign users in EO – the system hangs.
This whole site is built to support a calendar, so there are not many additional plugins. It is multisite with Elementor, Crocoblock, Essential Addons. We changed the theme and followed the instructions above. Thank you.

Ok thank you Basilis, Artem,
I have tested the method of customizing the mail by modifying the CSS within the PHP file and this works, there is however 1 thing that is preventing me from advancing. When changes are made you need to receive the confirmation e-mail again to see if the changes made look right, and this in a few rounds until the finetuning to reach the desired result has been achieved.
However, to receive the mail you have to register again which you already are. Even if I delete myself as user RSVP’d and clear the browser chache (I have tried al kinds of things) I still receive messages like ‘you can only register once to this event’, so preventing me from RSVP’ing again to receive the confirmation again.
(the resend button on the jpg attached does not seem to do anything, I do not re-receive the mail)
How can I do this ?
Thanks both of you for the replies.
I look forward to sorting this out.
I totally understand also about customizations not lasting forever, however, within a month or so of doing it, there was an update and I explicitly waited until it was confirmed that doing the update wouldn’t break the customization, but it did. 🙁
Was this feature ever created? I am looking at purchasing this addon and this is what i need specifically.
Hello,
Could you try replacing ux_val=”3a” with ux_val=”3″?
Hey Jan,
We will push the problem fix in some time, we appreciate your understanding and patience!
You are welcome!
You know, anything else just let us know 🙂
Hi Stef,
no there is no easier way, you will still need to modify the templates, we do not have the modification added on the plugin unfortunately!
Hello,
Unfortunately, only one way of customizing the email template. However please create a new ticket and select Feature Request as category so others can vote on your idea and get it moved into development faster.
Hi,
It seems that there is no actual issue from WordPress then.
Could you please check over to your hosting provider please?