Robotism
Be careful with this. A lot of early marketing and youtube videos show they're able to mix with a lot of stuff, when I tried it myself I ended up with goop. They changed the recipe or lied in the marketing, customer support ignored me and many others when we wrote to them asking what was up with the mixing problems.
Not sure what you used for thinner but their website says Real Color is acrylic lacquer. It says their own Real Color thinner works great and other thinners for acrylic lacquer from other brands. Then it says non vinyl lacquer thinner and alcohol. So those appear to be the choices, something like x22 Tamiya ( basically an alcohol thinner), isopropyl, lacquer thinner. Beyond those you might be getting into trouble. I haven't tried these paints yet but they sound interesting.