Invalid Float Literal

I am writing a fair number of f64 numbers to an .ssv file and later reading them back.
It always worked just fine but now I am getting the above error when reading and parsing as f64 this value: 49.6643523529881. All the other similar numbers are just fine. Either I am doing something very silly, or it is a very peculiar bug?

I think you'll have to provide more context. In a simple example parsing this literal works fine.

It seems to work fine on the Playground. Can you share some more code/context?

Thanks for checking.
I must remember to use the playground next time myself.

I think maybe I have some corruption in the file. I will regenerate it and see how it goes.

Yes, it was something wrong with the file, sorry about that.
I was led astray by reading about Rust issues with parsing floats.