Hi - i bought a Samsung S21 Ultra 5G (model SM-G998U1) it arrived complete with a dual SIM cradle.  I have 2 x UK SIMS (both work when placed into SIM1 slot of the cradle). I check 'About Phone' it shows 2 x available IMEI numbers.  I have reset network setttings, rebooted into safe mode - SIM2 does not show up here either.  No matter what I do i cannot get SIM2 to recognise there is a SIM card in the SIM2 slot.  I am up to date on software updates (current is on One UI version 7.0, Android 15, Baseband version G998U1UESGHYF1)

What is the problem with this please? I don't have eSIMs installed, the two physical SIMs both work in the S21 when placed into SIM1 slot, there seems to be a software issue that prevents recognition of the two SIMS being inserted together.

I was under the impression this phone could handle 2 x physical SIMs, but my handset cannot even see the two together?