Yep really normal and I know it must be really hard but you will get there just keep trying, even if they sleep for half an hour or an hour in it for one night and you increase the time slowly that’s a win! Mine didn’t for a while but like Kirsten said I popped a hot water bottle in before she went in and also my t shirt so it smelt like me and it seemed to work.
We survived this stage by co sleeping. She would only sleep if in physical contact with me, so co sleeping was a life saver otherwise I wouldn’t have slept at all!
Its so normal! Have you tried popping a hot water bottle in the cot to warm it up a little and moving it before popping them down? So they are not being placed on a cold surface? Used to work quite well with my first.