\ Operator with SparseMatrixCSC blocks calls dense Solver

Thanks for the nice package.
Recently, I noticed that if the blocks are of type SparseMatrixCSC a dense solver is called. Is this intended or known?
MWE:

julia> using BlockArrays

julia> using SparseArrays

julia> blocktest = BlockArray(sprand(4, 5, 0.7), [1,3], [2,3])
2×2-blocked 4×5 BlockArray{Float64,2,Array{SparseMatrixCSC{Float64,Int64},2},Tuple{BlockedUnitRange{Array{Int64,1}},BlockedUnitRange{Array{Int64,1}}}}:
 0.0  0.16344    │  0.331454  0.0       0.0
 ────────────────┼──────────────────────────────
 0.0  0.0121386  │  0.411176  0.399074  0.267498
 0.0  0.321397   │  0.602725  0.0       0.105105
 0.0  0.402935   │  0.383906  0.897609  0.477092

julia> b = ones(4)
4-element Array{Float64,1}:
 1.0
 1.0
 1.0
 1.0

julia> @which blocktest \ b
\(A::ArrayLayouts.LayoutArray{T,2} where T, x::AbstractArray{T,1} where T) in ArrayLayouts at /home/max/.julia/packages/ArrayLayouts/9PQtL/src/ldiv.jl:145

julia> sparsetest = sprand(4,5,0.7)
4×5 SparseMatrixCSC{Float64,Int64} with 14 stored entries:
  [1, 1]  =  0.00801114
  [2, 1]  =  0.806908
  [1, 2]  =  0.565691
  [2, 2]  =  0.120568
  [4, 2]  =  0.934967
  [1, 3]  =  0.0708214
  [2, 3]  =  0.287633
  [3, 3]  =  0.0779688
  [4, 3]  =  0.867172
  [3, 4]  =  0.681556
  [4, 4]  =  0.873379
  [1, 5]  =  0.425396
  [2, 5]  =  0.836935
  [4, 5]  =  0.944869

julia> @which sparsetest \ b
\(A::SparseArrays.AbstractSparseMatrixCSC, B::Union{AbstractArray{T,1}, AbstractArray{T,2}} where T) in SparseArrays at /usr/share/julia/stdlib/v1.5/SparseArrays/src/linalg.jl:1460

Start with the Julia MWE and compare the displayed dispatch locations in ArrayLayouts/src/ldiv.jl:145 and SparseArrays/src/linalg.jl:1460. Trace how a BlockArray containing SparseMatrixCSC blocks selects its solver, then verify the intended behavior with a focused regression test for the shown operator and vector.