P3D v18.104.22.168077 here. LIMN opens without troubles at my side, using ADE v01.76.6715. You should possibly update ADE to latest version.
Checking the path of your P3D4, it looks as it is installed inside one of the standard Microsoft Program folders that are heavily controlled by the system about read and write rights by the user. Suggest you check your UAC and lower the control level, or manage, next time or next update, to install your flightsimming related softwares (including ADE) outside the Program Files (x86) or Program Files folders.
Just my 2 cents
you bet deserve a feedback.
UAC should not represent an issue since ADE is run as administrator (I need to find now a way to run it as standard user, that means skip UAC).
I tell you what I did.
I checked that the ADE installation reads the registry but it appears that doesn't write on it.
So I simply moved its directory outside Windows programs folder and I uninstalled it to clean the installation log.
Then I authorized ADE to make the update.
Now it runs well and I got the airport LIMN.
I would suggest you keep ADE being run as administrator...
At my side, all my flightsim related softwares are outside the MS Program Files, and run as administrator, consequently no troubles with the write or read rights, and I have no troubles so far. I must also say I am the sole user of my PC, so I assume I know what I do with my machine
Caution! ADE is pretty addictive....