Most of those service personnel affected have now returned to duty, but Pollard told MPs on Thursday that he was angry he had not been given all the information and said the programme had been put on pause while further investigations took place.
In November, Pollard, announced that Ajax had reached its “initial operating capability” – a significant milestone.
The multi-million pound vehicles, made in Merthyr Tydfil by General Dynamics, were originally due to enter service in 2019.
But the £6.3bn project has been criticised for being poorly managed by the Ministry of Defence and was paused in June 2021 due to concerns over vibration and noise causing hearing loss to those training.
Trials on Ajax are set to resume soon, before a final decision is made on its future.
The British Army has ordered 589 Ajax armoured vehicles at a cost of more than £5bn.
The programme is already eight years behind schedule.
Conservative Shadow Defence Minister Mark Francois said it was time “to fix or fail Ajax, once and for all”.