That's a conundrum @Hannah352
Try https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may also need to insert your earphones and or hook up to a laptop. No need to launch anything, just turn it on. But if that does not work then consider a back up and factory reset if the idea by @AM4N does not help.
I wish you all the best.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb.
Samsung Gear s³ Frontier Watch.
Samsung Galaxy Watch⁴ Classic.
The advice I offer is my own and does not represent Samsung’s position.
I have no affiliation with Samsung.
Am having the same issue as you since the last update UI 4. Have been using dual sims on my s10e for several years without issue but since this update the 2nd sim has stopped functioning can't even register with network operators. Have tried all usual solutions but only the sim in position 1 will work. For the moment having to use 2 phones. Hopefully Samsung will launch a new update soon to rectify this mess.
Mines same. I done the 2nd update lately and when I go onto settings, the card comes back again but then 2 mins later says not detected. I hope they fix it asap