I have the same issue with a 3-way non-neutral setup. I’ve just assumed it is because of the non-neutral, and plan to rewire to have neutral at some point (probably when I’m done upgrading everything to smart switches). That will be better too, because then I won’t have to rely on this aux switch, which is more limited. I plan to get an Inovelli switch set up via direct association.
Another solution might be available to you once the new Inovelli pico remote is available (project BFF). It was originally scheduled to come out in 2020, but now looks to be coming out in beginning of 2021.
Paddle Remote | Project BFF - News, Updates & Roadmap / Product Roadmap - Inovelli Community
2020 Product Roadmap - News, Updates & Roadmap / Product Roadmap - Inovelli Community