You should not. All those built in apps use DD+ which carries lossy atmos. Lossy atmos can be sent via both ARC and eARC no problem. Both the GX and q90r have eARC so you can also hook up a 4k blu ray player and pass lossless atmos via dolby trueHD. I'm not sure about the GX, but I know other 2020 LG oled's have dropped support for dts passthrough which is only used for physical media like blu ray. Luckily the q90r has two HDMI inputs, and it plays dts, and dts:x. If you hook your blu ray player up to the q90r you should be able watch about anything and everything with no problem.
I have an older LG oled, the e8, which only supports ARC. I'm able to get atmos from built in apps, and have no lip sync issues (a potential problem with ARC, but not eARC). I plug an nivida shield pro, and a 4k blu ray player into the bar for lossless audio and passthrough dolby vision and other 4k hdr just fine. If you have any problems it most likely a defective bar or tv. Just make sure you have decent 4k cables