I'm wondering if your daughter has a sleep association problem with her cot/bed? I know that when I did some training for my own insomnia, you are supposed to keep your bed for sleep and not for play, work, reading or watching TV. Does she have a lot of toys in her cot? If she does I would take most of them out and leave only a couple of soft toys. Also some of the suggestions on the sticky at the top of this forum (the one about 23 months who needed a cosy cot and wind down time) might work too.
She might need help with processing her day because she talks to herself a lot before sleeping. Before bed might be a good time to talk with her about what you did during the day in a sort of conversation, even if you don't understand what she saying. I do this a lot with my son., I think it helps.
I'd also get your husband to sleep in her room for a couple of nights, and when she wakes up to say to her in a firm voice ' Time to sleep' so that she knows that her cot and night time are for sleeping. No responding to games, or conversation. Try for 2-3 nights and see if it helps.
Also during the day if she's playing in her cot for more than 20-30 minutes and not sleeping take her out, read her some books, wind her down and try putting her doiwn again in 30-60 minutes when she's calmer and more relaxed. Again, so that she knows that when she's in her cot it's time to sleep.
Don't know if this will help, but everything else doesn't seem to be working for you.
Lan