@oliverthom707 Of course, it is possible, but somehow not very effective to build. I would consider doing it with a Material Table by Scrounger or just using Buttons in VIS. If created by hand we can´t get big HTML Tables to work properly.
Why is ON_SET empty for the dimmer device? It needs to point to the state that swichtes on / off the light. The _SET always means "send a command here" and _ACTUAL means "read status from here". _ACTUAL is optional and usually is not needed to be filled (if you just have one state for an action, fill it in _SET and leave _ACTUAL empty). That might already be the issue (or not, because the state seems to exist?). (And yes, that is not really documented anywhere, is it?).
Also it is not necessary to create two devices for the Bulb. The dimmer can also switch on/off the lamp (since you also fill in the same state in ON_SET/ON_ACTUAL, right?). As you can see in my screenshots I created a device that has on/off, dimmer, colortemperature, color (rgb string & hue). All in one device. The type-detector will try to use the device that maximizes the states used, i.e. the bulb will be detected as color capable and will have all the other capabilities, detected, too. So if you do not have a concrete usecase for the "light" device, I'd scap it.
Another issue could be that lovelace tries to create two entities with the same name (I think it should try for your naming scheme) and that is not possible in homeassistant and currently one of them is discarded. You might want to take a look at the debug log for this, yourself. It should state something like that (it is not a warning anymore, because entities are recreated all the time and there seem to be valid cases where duplicates are expected... not sure... might look into that again, sometime).