Just to offer another POV. Im the child who would say my mum is anxious, and she's the mother who would refuse to accept that and would think I'm being ridiculous.
If I tell her of any minor problem or worry in my life, her reaction is somewhat extreme. I think this is her attempt at empathy, or trying to sympathise and then fix things for me? It can be a minor issue (to me) that I'll be moaning about in an offhand way, in the way my friends and i will vent about work etc and She'll react in a way like it's a catastrophe, offer multiple implausible and unasked for solutions, and then follow up by asking about it for days after, urging me to find a solution, when I'm not particularly bothered about it any more.
I've interpreted this as her being anxious and it's stopped me sharing any minor stressors with her because it doesnt help, it makes it worse if anything.
From her point of view, perhaps she feels like she has to find solutions to my problems because she's the parent and I'm the child? I'm not sure.
Anyway, perhaps your DD feels the same. Maybe your response to her worries seems like youre overly anxious to her, and it's made her feel unable to share with you any more.
Regardless, I think you should go for talking therapy to seriously try to uncover what she could mean. You're currently bring extremely dismissive of what she feels, calling her reasons "incoherent". They're obviously very big, clear, and real to her.
Once you've committed to therapy, perhaps she'd be willing to engage in group therapy with you and her dad.
You won't rebuild your relationship with her by continuing to deny any part in your estrangement.