Histogram Stuck Left - Sony a7iii

Hey there experts,

Tonight is my second night imaging, and I'm in the middle of capturing exposures as I type this, but I've been having an issue with my histogram while setting up for my sequence.

My histogram stays against the left edge of the graph, and does not move right no matter how high the ISO is and how long the exposure setting is.

Granted I'm not using an optimized astro setup, my gear is certainly capable as I successfully imaged the Orion Nebula the other night in pretty good detail for my first try at capturing and processing. Also my exact camera and lens have been used by another person to capture some incredible stacks.

This histogram is functional, when I took my flats, it changed to roughly the middle.

Here's what I'm using:

Camera: Sony a7iii (firmware fully updated) - 1600iso, f6.2 (minimum), 600mm
Lens: Sony G OSS SuperZoom 200-600mm

Exposure: 30s
ISO: 1600
F: 6.2 (minimum)

Could it be that I'm fully zoomed at 600mm? Could this be a situation where the histogram isn't the law to follow?

Total noob, absolutely obsessed, happy to be here, thank you so much for any help.

Clear skies!