RandExpand does not expand bond dimension when conserving momentum

[AFeuerpfeil]

When conserving e.g. momentum for the following product state MPS (1st charge is particle number, 2nd is crystal momentum), RandExpand fails to expand the state because the expanded auxiliary space is projected out.

The left virtual space is given by

6-element PeriodicVector{GradedSpace{ProductSector{Tuple{U1Irrep, ZNIrrep{36}, U1Irrep}}, TensorKit.SortedVectorDict{ProductSector{Tuple{U1Irrep, ZNIrrep{36}, U1Irrep}}, Int64}}}:
 Rep[U₁ × Cyclic{36} × U₁]((0, 0, 0)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((2, 7, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((1, 8, 1)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((0, 9, 0)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((2, 34, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((1, 35, 1)=>1)

The physical space is given by:

6-element PeriodicVector{GradedSpace{ProductSector{Tuple{U1Irrep, ZNIrrep{36}, U1Irrep}}, TensorKit.SortedVectorDict{ProductSector{Tuple{U1Irrep, ZNIrrep{36}, U1Irrep}}, Int64}}}:
 Rep[U₁ × Cyclic{36} × U₁]((-1, 1, -1)=>1, (2, 7, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((-1, 1, -1)=>1, (2, 13, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((-1, 1, -1)=>1, (2, 19, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((-1, 1, -1)=>1, (2, 25, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((-1, 1, -1)=>1, (2, 31, 2)=>1)
 Rep[U₁ × Cyclic{36} × U₁]((-1, 1, -1)=>1, (2, 1, 2)=>1)