JEM 4.5 Attachments failed

I tested on Demo on J5.4.7 with JeM 4.5.0 and attached a Pdf.
The only problem is that all is quite new or other.

So why does nothing appear when I click "+", whereas I don't have this problem with the "links" tab?

 
Result
 
 

This may be caused by the page JavaScript not loading or being blocked.
The + button needs JavaScript to display the attachment upload fields. Please try:
- Reload the page with Ctrl + F5.
- Try another browser or incognito/private mode.
- Temporarily disable browser extensions such as ad blockers.
- Check that JavaScript is enabled in the browser.

If it still fails, open the browser console with F12 and check for errors after clicking +.
If there is a console error, please send us a screenshot so we can investigate.

And if your Joomla is 5.x, you can donwload JEM 5.0.0 from:
www.joomlaeventmanager.net/download

Why, after the update to JEM 4.5, the "media\com_jem\attachments" directory where attachments should be located does not exist

Yes, that can happen.
After updating to JEM 4.5, the folder: media/com_jem/attachments may not exist yet. JEM uses this as the default attachments path, but the folder is normally created when the first attachment is uploaded.

So this is not necessarily an installation error. Please check in JEM settings, confirm the attachment path is: media/com_jem/attachments

Make sure the Joomla media/com_jem folder is writable by the web server.

And try uploading an attachment. JEM should create the required subfolder automatically, for example: media/com_jem/attachments/event123

If the upload fails, the most likely cause is folder write permissions or an incorrect attachment path.

"Did you have any attachments before, and were they lost?

Tell me if it works.