I have mavic crossrides with spesh purgatory and have done the duct tape with stans sealant approach.

Worked with track pump and looks seated and will inflate to good pressure but loses it over a couple of days. Do I need more sealant (used 90ml for 2.3 in tyre) or is it not seated properly or is it something else

Advice much appreciated

Can you still hear sealant sloshing around? If not then stick a bit more in but otherwise pump it up and go for a ride. It can take a while to fully seal and you’ll need to pump a bit more air in from time to time.

Mine took about 36hrs or so to stop losing pressure.
Think I had a bit more sealant than you but not loads. I also used Gorilla tape on non tubless rims btw.

Si

Is it proper 2bliss? Might need a bit more sealant if not. I’d put about 120ml in a 29er tyre of that volume, so chuck a bit more in and go for a ride. Should sort itself out.

I don’t have any tubeless tyres that will hold riding pressure for more than about a week, I just top up every now and then the few psi required.