Eh, I tried in 2017 with BA when their system went down and received nothing. There was magically a Black Lives Matter protest at Gatwick (or maybe LCY, can’t remember) on the same day, which isn’t covered apparently.
I think the qualifying rules may have changed since then.
The legislation is on the link below, it might be worth a once-over with your chat bot of choice to understand out if your circumstances are covered:
I believe the compensation part only kicks in if it’s the airline’s fault.