backward solve tutorial - pole vector problem.

[Run_Dos_Run]

Please help
I created a backward solve following this tutorial:

Create a Backwards Solve in Control Rig | Tutorial

The forward solve was here:
(Creating and Modifying Control Rig | Course)

There is a problem with the pole vectors, but only in backwards solve. Whenever I apply the layered control rig in the sequencer, the polevectors (elbow joints / knees ) move by a small distance. It seems to be related to the parent constraint node. But I cannot figure out what causes the issue.
Any ideas?

[Run_Dos_Run]

A tutorial mentioned, the polevector needs its own setup in the backwards solve. something like this:

Where I add the offset to Y. But this does not work perfectly too…
Shouldn’t this work, even without construction setup?