It works fine for me; can you confirm it doesn't work when it's the only plugin installed and include the console output when the server starts up?
Ok, my bad!! I got mixed up on Poggit-Orphanage between 3 versions having forked Darunia's AlwaysSpawn not realizing that it was Shoghicp who forked it and fixed/added things along with one of the original authors - so no PR's were made to the original repo. Shoghicp's is at https://github.com/shoghicp/AlwaysSpawn and is, I think the one to use; but I'm going to have to test them all again. I was also using DA_Swagnemite's version from the orginal forums http://forums.pocketmine.net/plugins/alwaysspawn.284/, which works too, but his github at https://github.com/DASWAGNEMITE is now empty, and that's why I ended up forking the mess in Darunia's repo by mistake (that could never possibly had worked!). Sorry for the confusion, I'll sort it out, and thanks IG.
As simple as this plugin is, It turns out that the code of the approved .phar on the original forums isn't the same as any of the branches in either of the repos I mentioned above, so I've released it as a new branch in the poggit-orphanage fork of the original repo: https://poggit.pmmp.io/p/AlwaysSpawn The version I thought I had originally added to Poggit was https://github.com/shoghicp/AlwaysSpawn/tree/master/Plugin/New-API/AlwaysSpawn, which also has a few commands, but for whatever reason they didn't make it to the official plugin release.