Does your plugin appear in the "New recipe" menu ?
* If it does, then to make it also appear in the dataset actions, you need to add in the recipe.json file a line like: "selectableFromDataset": "main", Where "main" must be replaced by the name of the input role in which the "current" dataset will go
* If it does not, then it means your plugin does not work properly, probably because of a parsing error somewhere. In the dev section, do you see warnings about components not loaded ? You can also check the backend.log file for errors loading that plugin
Thanks for your answer ! The recipe.json had the "selectable from dataset" line and the plugin worked properly. The issue was that the folder in which I had the recipe.py and recipe.json files (let's call it the 'recipe folder') had the same name as another 'recipe folder' from another plugin...