I recently made the switch from the Pixelmon Reforged Technic modpack software to a Magma server for extra plugin and mod support. I installed the individual mods for Pixelmon Reforged and Biomes O' Plenty, but unfortunately, after said switch I noticed that the NPCs from Pixelmon no longer spawned in Poké Marts and Pokémon Centres, nor did they spawn in gyms. After experimenting with the NPC Editor tool, I discovered that they were despawning once players moved too far away. I looked online for people with similar problems, but unfortunately couldn't figure out what was causing this.
Upon taking a closer look at the modpack's files, I found that the Technic modpack included several sidemods that my world had been saved with, namely Pixelmon Extras, Gameshark and Biomes O' Plenty Patcher. I've looked into what those mods do, and while I don't think they're the cause of the problem, I can't be sure because I was unable to find and test them on Aternos' mods page. I did check the forums to see if they'd been requested, and it seems that Gameshark was available at some point, but due to the lack of an API to collect the data from Reforged's site all of these mods are not supported.
For additional context, I also installed the mods IV Chain and Traveller's Backpack, as well as plugins ImageOnMap, SkinsRestorer and ProtocolLib. I switched the server to offline-only mode as well. Has anyone seen this issue?