Q Light Controller+

I have downloaded the latest Raspberry Pi release dated 20240606.
I have set universe 2 for GPIO input.
I have added a 1k resistor between pin 1 (3.3v) and pin16 (GPIO 23)
I have set GPIO to input, DMX24 in universe 2
I have added a single generic dimmer universe 1 DMX1 and created a scene with that item
I have added a button in the virtual console, set the function to the scene and input universe 2, DMX 24

When I boot the PI, I am able to use the screen to turn on and off the button. If I short GPIO to GND, it will switch it.

As soon as I release the GPIO, the button continually switches on and off.

I have connected GPIO23 to 3.3v, bypassing the 1k resistor and the button continues to flicker on and off

I have tried it on a PI3 and a PI4, same result.

Typically, a GPIO port has Three states: on - off and in-between.
You must ensure it sees the correct signals: pulled high or drawn to GND. (While doing so, a Schmitt-Trigger IC may protect your GPIO ports—replacing the IC will save the PI from being killed.)

I'd start by looking at the signal levels outside of QLC+ (there is a tool for that, which one I don't remember by hard). If this tool shows you it's flickering, the signal is invalid.
QLC+ needs a rising edge to trigger things. off -> on sets the input, on -> off does not do anything, off -> on (re)sets the input again.

I used the command
raspi-gpio get
it returned
GPIO 23: level=1 func=INPUT pull=DOWN

so with the 1k resistor, despite the internal pull down, it is registering 1. I get 0 when switching to gnd, so the pin is working as expected.
If the level is 1, I am getting the button continually switching state. it stops whenever I ground it.