GaussianBinaryRBM gets very similar fantasy particles

I created my own GaussianBinaryRBM ``` function GaussianBinaryRBM(sz::Union{Int,Dims}, szb::Union{Int,Dims}) b = zeros(Float64, szb...) w = zeros(Float64, sz..., szb) return RBM(Gaussian(Float64, sz), Binary(; θ = b), w) end ``` and fed real valued MNIST data into it. after training and generate fantasy particles by pcd, I get synthesized characters back, in addition to being noisy, there is no variability in the output images. <img width="648" alt="gaussian-binary-fant" src="https://github.com/cossio/RestrictedBoltzmannMachines.jl/assets/1161170/f520be10-801f-4436-ad1b-9452480f58dc"> is there simple reason why this is?