How frame command with address works

Greetings,

I have to analyze a coredump on an Aarch64 system. The callstack is broken so I only see the bottom frame. However, if I manually unwind the stack via $x29 register then I see what looks like intact stack frames. Now I try to use the frame / frame address command with the addresses from the $x29 registers which should point to the bases of the stackframes (the location where the address of the next frame is). However it always tells me "No frame at address ...".

What does frame address need to correctly parse a frame?

Regards