I have gone through this for a year with my 5 year old- I left it in the end and she finally started last month to read aloud. I don't know what it was- stubborness, fear of making a mistake? don't know. Try not forcing the issue and see.
Are you the one trying to help her with her homework, or do you just want her to read to you as a separate thing? If she's already done "what she has to" with someone else, she may not be keen on being pushed to do more by another person. I would never have read aloud to anyone at that age if I hadn't been required to as homework.
For what reason are you trying to get her to read to you?
If not homework - don't push it,
If homework - just leave her to do itl fill in the gap or encourage her to sound out (even if you know she knows it) - and i her school reading record book note down any difficulties you encounter, such as words not remembered.