dmrg_x does not support write to disk

Here is a minimal code:

using ITensorMPS
let
    N = 10
    sites = siteinds("S=1/2",N)
    os = OpSum()
    for j=1:N-1
      os += 0.5,"S+",j,"S-",j+1
      os += 0.5,"S-",j,"S+",j+1
      os += "Sz",j,"Sz",j+1
    end
    H = MPO(os,sites)
    nsweeps = 3 
    maxdim = [10,20,40] 
    cutoff = [1E-10] 
    psi0 = MPS(sites,[isodd(i) ? "Up" : "Dn" for i=1:N])
    energy,psi = dmrg_x(H,psi0;nsweeps,maxdim,cutoff,write_when_maxdim_exceeds=20,outputlevel=1)
end

And here is the output I got, at sweep 3 it should start writing to disk

After sweep 1: maxlinkdim=4 maxerr=1.04E-16 time=0.009
After sweep 2: maxlinkdim=16 maxerr=3.24E-11 time=0.162
ERROR: MethodError: Cannot `convert` an object of type Vector{ITensor} to an object of type SerializedElementArrays.SerializedElementArray{ITensor, 1}

The issue appears to be associated with DiskProjMPO(...) in abstractprojmpo\diskprojmpo.jl but it's unclear to me how to proceed from there.

Run the minimal Julia reproduction and confirm the failure at sweep 3 when write_when_maxdim_exceeds=20. Then inspect abstractprojmpo/diskprojmpo.jl, especially DiskProjMPO(...), and trace the Vector{ITensor} to SerializedElementArray conversion. Done means dmrg_x proceeds past sweep 3 and writes to disk without the MethodError.