palosutca Hello
First, using JA Extension Manager to update extensions is not the only way to update. It's the easiest way however you can choose to update the extensions manually in case there's temporary issue with JA Extension Manager.
Second, you only provided us access to your one site in OP and we can only help you to look at the issue at that one site only. If you do not share with us the info of your other sites then we cannot help with them.
Our team has tested JA Extension Manager at our end and it's still working fine. This means it's a specific problem at your site.
Since the problem is not with any other extension but only with the JA ACM version installed at your site (2.1.4 version), please grant us permission to re-install this version so that we can test further with the update. We didn't know if you have done custom work with the JA ACM module that's why we wanted to ask for permission first before going ahead and re-install it.
EDIT: We also need your permission to back-up your site so we check locally. Please confirm.
