Mouse Click not Working

See if you can boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

The " Hover " feature is Located as per image below

As for Click does not work - how is the Battery charge

Other Features available for the Magic Mouse are listed in System Setting >> Mouse

Refer to images below

Point and Click

More Gestures

The Tinkerer wrote:

How can I check what 3rd party extensions are loading that might cause the problem?

Download and run Etrecheck.  Copy and paste the results into your reply. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Additional Text button to paste the report in your reply.

Then we can evaluate the report to see if we can determine the cause of the problem.

Ah, the other Hover

Well, this machine appears to have several issues

That said, thing it wettest to focus on the Kernel Removal before moving on the more Cosmetic Issue like Dock Animation and moues issue

Once the Kernel Removal issue is resolved, post back to that issue is hopefully fixed.

Then we can collectively look at the other Cosmetic issue