I would recommend you to disassemble the shifting block completely (the one which actuated the gear hub), inspect it, inspect the seals, clean it, lube it, assemble it back and fill with fresh hydraulic fluid (I filled mine with Magura Blood Hydraulic mineral oil). The mechanism of the shifting block which connected to the gear hub is pretty simple, so it should be easy. You might want to see what is going on on the shifter lever mechanism if rebuilding the shifting block will not fix the issue.
Your thorough feedback assisted me to find another possible solution.
If I may use your image.
The following resolved the shifting matter for me
Bend the spring loaded plate underneath the pawl back slightly, to ensure that it keeps the pawl in position.
Slide the retainer out to do this.
From what I saw it looks like this insures that the pawl will follow the designed and desired path to be out of the way after the shift, or engaged when shifting is required.
The image might do a better job at explaining.
It is however crucial that you ensure all the air is out. Tilting the onesie while bleeding resulted in air trapped in the chamber to move out, while bleeding.
This Kindernay now “Shift”’s


, so nicely.
Hope this helps someone!