I had the same issue and figured out that the reason it wasn't showing up is because I had another Alaska Airlines file that had the same name.

What you need to do is go into your community folder and find this livery. I rename all of the liveries using the same format to make sorting easier. So I renamed this folder Asobo_A320_NEO-Alaska_M2L. Obviously the M2L stands for more to love and sets it apart from my other Alaska livery.

Next go into the folder and double click SimObjects then AirPlanes. Rename that folder Asobo_A320_NEO-Alaska_M2L as well.

Here is the tedious part, you will need to go into the layout.json file and open it in notepad. Every single line that begins with (***it is important to note that this is NOT the full line entry, only change this part of the text up to the next slash***) "path": "SimObjects/AirPlanes/Asobo_A320_NEO-ALASKA/ needs to now be changed to "path": "SimObjects/AirPlanes/Asobo_A320_NEO-ALASKA_M2L/

This should fix everything and both of your Alaska repaints will now show. As always make sure you have backups of both files.