Cartesian-Polar 2D in flat space

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Needs["xAct`xTras`"]

Define manifold, metric, derivative and charts

Define a 2D manifold ℳ, metric g with its Levi-Civita derivative and cartesian and polar charts

$DefInfoQ=True 
(* evaluate this cell if you wish to see all related tensors being defined *)

DefManifold[ℳ, 2, IndexRange[α, η]]
DefMetric[1,g[-α,-β],CD,SymbolOfCovD->{";","∇"}]

DefChart[cartesian,ℳ,{1,2},{x[],y[]},ChartColor->Blue]
DefChart[polar,ℳ,{1,2},{r[],θ[]},ChartColor->Red]

Define a flat metric

cartesianMetric=IdentityMatrix[2];

MetricInBasis[g,-cartesian,cartesianMetric]//MatrixForm

Changing basis & coordinates

Define the coordinate transformations between the charts

From polar to cartesian:

x/:InChart[x[],polar]=Function[{r,θ},r Cos[θ]];
y/:InChart[y[],polar]=Function[{r,θ},r Sin[θ]];

From cartesian to polar:

r/:InChart[r[],cartesian]=Function[{x,y},Sqrt[x^2+y^2]];
θ/:InChart[θ[],cartesian]=Function[{x,y},ArcTan[x,y]];

$Assumptions=And[{x[],y[],r[],θ[]}∈Reals,r[]>0,0<θ[]<2Pi]

Display the transformation matrices

With xCoba 0.8.3   ComputeBasisValues[cartesian,polar]   works well as you see below

ComputeBasisValues[cartesian,polar]

However using xCoba 0.8.4 it does not work anymore

MatrixForm/@ComputeBasisValues[cartesian,polar]