Jose,
Can you provide a bit more detail? Did you group them in Roon or BluOS. Did you group them in one and try to ungroup them in the other?.. The grouping function is different between the two, so it could partly explain your issue.
Also what do you mean “additional hardware” required for Roon? If you have a computer with your music files on it, there is no additional hardware. If you were simply using Tidal + a USB drive on one bluesound device, or a NAS, I could see your point… the big advantage of Roon is that many people will experience an INCREASE in hardware given that they are no longer constrained to (in this case) a BluOS ecosystem. For example an old IOS device or android could be the “endpoint” for a new room, without requiring you to purchase another BluOS device.