Puppy settles in or outside pen but won’t take herself into the crate to sleep

My 22 week old Cavapoo puppy is comfortable with her crate, and settles in it well when we put her in there for enforced naps, but doesn’t seem to naturally see it as a place of rest.

We have a set up for her where her crate is joined to a pen. The pen helps restrict her space while we get on with chores etc. Often when she is tired, she will happily lie down and settle on the floor either inside or even outside the pen but never really takes herself into the crate.

We would love for her to see her crate as the ultimate place of rest rather than simply a place for enforced naps. In general, she doesn’t fall asleep outside of the crate. She will settle but not physically sleep until she’s very very tired or we enforce a nap.

Any ideas on how to get her to take herself into the crate when she’s tired please?