getCallbackSolution failing and yielding error 422 inside a chgbranchobject callback?

Thank you Daniel for your reply and sorry for my laconic one,unfortunately I got my account blocked for whatever reason as I tried to attach multiple screenshots.This time I'll paste the code as plain text,for good measure.After the model definition we have:

class controldata:

 def __init__(self,inputdata,outputdata,bestbound,nodenumber,brancher,threshold,threshindex,Mleft,Mright):

   self.bestbound=bestbound

   self.inputdata=inputdata

   self.outputdata=outputdata

   self.nodenumber=nodenumber

   self.brancher=brancher

   self.threshold=threshold

   self.threshindex=threshindex

   self.Mleft=Mleft

   self.Mright=Mright

controlmatrix=controldata(X,y,10000,[],[],[],[],[],[])

(An object to be passed to the callback,useful only for providing the input and output samples X and y,most of the attribute lists were meant for an early implementation and will stay empty)

def spatialbranch(prob,obj,obranch):

  N=np.shape(obj.inputdata)[0]

  X=(obj.inputdata)

  y=(obj.outputdata)

  h=math.floor(0.8*N)

  sol=prob.getCallbackSolution(z)

(The actual callback,up to the point where the issue is encountered.We might argue that z is not defined inside the function,but only as an xpress object of the prob we'll pass as input argument;still,even using getCallbackSolution() with no argument inside the brackets to get the full solution will result in the execution stopping with error 422).

I add the callback to the problem with p.addcbchgbranchobject(spatialbranch,controlmatrix,5),and I then optimize with p.mipoptimize().

As for the CSV file,it's one of several regression datasets available on Kaggle as part of the Starter: R robustbase Datasets 6f223ec8-4

package;I doubt the issue depends on how the CSV's are parsed,since optimization of the problem on the same dataset without custom branching will work fine.