Thank you for pointing out what was causing the issues, it's good to know these things in case other users have the same problem.
We found that ImageEffectCK was not intentionally blocking attachments. The problem was caused by a conflict between the JavaScript loaded by both extensions.
JEM’s attachment manager relied on jQuery and the global `$` alias. Other extensions can change how or when jQuery is loaded, causing the `+` button to stop responding.
In JEM 5.0.1, we have removed the jQuery dependency specifically from the attachment management functionality. It now uses native JavaScript and is isolated from scripts loaded by other extensions, including ImageEffectCK.
It should therefore no longer be necessary to uninstall or disable ImageEffectCK. After updating JEM, we recommend enabling ImageEffectCK again, clearing both the Joomla and browser caches, and testing the attachment form once more.
This change should also reduce the possibility of similar conflicts with other extensions in the future.
The commit to prevent this issue in the future is (don't use jquery):
github.com/jemproject/JEM-Project/commit/e6f52136b3aec6828636005c16871cf69327d058This
commit will be included in the next ZIP regenerated of JEM 5.0.1 Beta 1 with this fix from:
www.joomlaeventmanager.net/download/beta-versions
Thank you for reporting,
