The power HUD from Cyberware doesnt appear if IGI is present. Disabling IGI with the command doesn't fix it either. I've posted this on Cyberware's github too in case it's on their end.

Is it hidden even if the IGI overlay is active?

Yes.

Unless he's rendering it using the debug event (F3), normal text (usually also on F3) or the potion event when the overlay is disabled in IGI it's most likely on their end then. But I'll have to check their code. Relevant IGI code.

It does require an "augment" to see the HUD so maybe it is a potion effect. I'll update the cyberware issue with this info, thanks.

I found this in a similar file in the Cyberware repository: Link
It does mention using the potion icons elementtype.

That is definitely it. It uses the potion rendering event to draw it's own HUD and IGI has the option to disable the potion overlay by cancelling the event. You can re-enable the potion overlay to (temporarily) fix the issue.

Code wise this can be fixed by using the net.minecraftforge.fml.common.gameevent.TickEvent event, TickEvent.Type.RENDER particularly.

Thanks a ton man. Enabling potion overlay does fix the issue at the cost of more ugly vanilla hud elements. I've posted this info to the cyberware github now.