No lending liquidity left when trying to margin trade?

Hi

I've had this happen several times. I transfer from spot to margin, when I try to borrow so I can margin trade I get an error along the lines of theres no funds left to borrow. It doesn't happen all the time but quite frequently.

Where does this limit come from? Is there anywhere to view like how much theyve have lent or how frequently they get more funds etc?

And does it apply to both cross and isolated or are they funded seperately?