i would not feel comfortable leaving a bike in a lock-up that is at the end of a dark alley
That is sadly, how insurances operate.
I kept my bikes for some years in an underground parking with 24/7 surveillance on-site, CCTV, garage was locked after 9pm (with the guard inside) opened up back again at 7am.
They agreed to insure me there (thousands per year), but at some point they deemed it not secure.
Shitty lock up at the end of the dark alley with cardboard door? YES THAT'S PERFECT.