Electroless nickel plating problem

I have a brass components (brass grade CZ121) which require electroless nickel plating (not electroplating).
I cannot get electroless nickel coating for my brass component from regular coating companies because of its complex geometry. Along with air agitation, special jig is required to enforce the coating solution to flow through intricate geometry of the substrate. I do it in the lab (I need this for rapid prototyping).
I use DC 1.5V for approx. 2min to kick off the process (+ goes to nickel cathode and - goes to brass).

However, I can get NI-P coating only when I keep DC turn ON. Once I turn off DC power then coating stops (checked experimentally for a few brass plates).
The coating solution was provided by regular Ni-P coating company.
I suspect that the problem may constitute the fact that Ni-P coating solution was stored unused for 3 months (in closed container with all ingridients mixed, ready to use).

Did anyone came across something similar?

If DC power is applied only for first 2 minutes of the process then after next 15 minutes of keeping brass in coating solution the substrate surface has red colour (it is supposed to have silver colour).
It seems that either a copper is being deposited on substrate (there is a brass or bronze component of the tank heater which is submerged in the solution) or some element is dissolved from substrate surface (zinc?) leaving mainly copper there).

Please help.
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