NPC spellcasters bugged

Hi. I currently have two 5e games I'm running as DM. In one of them, my homebrew game named "Amnesia Resurrected", all NPC/monster spellcasters are bugged. Their spells are simply listed in text and not filled into the new spell level tables. However, in the other campaign (Curse of Strahd) all NPC/monster spellcasters are ok. Any way to fix this?

Thanks for the answer Drespar, but unfortunately even if I create a completely new game the spellcaster NPCs are bugged. They have the new style spell lists, but they are not populated with spells. In Curse of Strahd they are populated.

This is the "Priest" NPC in my Curse of Strahd game.

This is the "Priest" NPC in a totally new game.

Curse of Strahd comes with Priest as a built-in character. It has the spells added. Even if you drag a fresh one into the Strahd game from the Compendium, it will only create an instance of the one already in the game.

Yeah. I did now notice this passage in the Wiki on Monster Manual:  Spellcasters:  There was an intentional decision made with spellcaster monsters where we limited the individual spell entries down to the most commonly used offensive spells. For those we created a separate actions for each to be rolled from the sheet. We went with this method instead of having an NPC sheet with every single spell inputted under Spellcasting to keep the attribute bloat low to keep your games optimized. That being said, any spellcasting NPC should have all their spells listed under their  Spellcasting  Trait on the NPC sheet when you do a drag and drop from the Compendium. Which REALLY makes me wonder, if this was so important due to keeping " attribute bloat low to keep your games optimized", why did they add all the spells to the characters in Curse of Strahd? This is kinda mindboggling... I can just import the CoS characters to the vault and then put them into other games... But why? I wouldn't be more than a few hours work for one person to go through MM and add spells to all the spellcasting monsters/npcs?

It's not the difficulty of adding the spells. Curse of Strahd is intentionally constrained by its nature as a module. In a homebrew game, there is nothing to keep a GM from adding a hundred spellasters or more, leading to bloat and loss of performance within that game. Although it is also possible to do that in a module, it is far less likely to happen, since the need for various types of characters has been anticipated by the creators. Curse of Strahd was presumably judged to be "OK" to expand spellcasting for, given the limited number of casters. --I really don't know if this is  the case, I am not privy to such details, so I am admittedly speculating.