Welcome! This works:
julia> a = [[[i+2*(j-1)+6*(k-1) for i=1:2] for j=1:3] for k=1:4]
4-element Array{Array{Array{Int64,1},1},1}:
[[1, 2], [3, 4], [5, 6]]
[[7, 8], [9, 10], [11, 12]]
[[13, 14], [15, 16], [17, 18]]
[[19, 20], [21, 22], [23, 24]]
julia> reshape(hcat(hcat(a...)...), (4,3,2))
4×3×2 Array{Int64,3}:
[:, :, 1] =
1 5 9
2 6 10
3 7 11
4 8 12
[:, :, 2] =
13 17 21
14 18 22
15 19 23
16 20 24
julia> ans[:]'
1×24 LinearAlgebra.Adjoint{Int64,Array{Int64,1}}:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
although I suspect there are more clever ways to do it. Note, the hcat seems to do the conversion as well.
PS: please quote your code: PSA: how to quote code with backticks