He reassured members their savings were safe and AmanhaNZ and the AmanahKiwisaver were financially sound.
Henry could not be contacted for comment.
A spokesman said the FMA could not comment as the matter was before the court.
In an attached disclosure notice, Henry said a number of allegations had been made against Amanah Ethical that it "totally rejected".
Directors had been accused of putting Shariah law ahead of the Financial Markets Conduct Act, Henry said.
In November 2017 the FMA had determined, without consultation with Amanah, that it had stopped managing the investments.
The FMA had "misinterpreted" a decision by the directors for a period of time last year to temporarily hold current investments and accumulate the further increments of money coming, pending a capital raising by the management company, Henry said.
Amanah had never stopped managing members money, he said.
Amanah had since been prevented from marketing itself and has needed the FMA's
permission to process new applications to join its KiwiSaver plan.
Amanah's website said its ethical mandate restricts investing activities to permitted investments and screens potential investments for prohibited activities including alcohol, tobacco and defence/weapons.