2. It is working for me. :X Are you sure you use the right trigger word? The trigger word might be different from the file name or what somebody wrote in civitai.
InvokeAi will write a list of trigger words in the console after it loaded a model, e.g. ">> Textual inversion triggers: <low-poly-hd-logos-icons>, etc". There you find the actual trigger words.
1. There is a limit of about 75 tokens, so if the negative textural inversions work, that's usually a good way to save on words. :)