Similar issue here with the latest iOS 18 beta. For us, the principal placement causes the tab bar to increase, while looking good with previous iOS versions.

Unfortunately it looks like this issue still exists. iCloud is selected as default keychain when opening the certificate. I tried @Najjii solutions and clicked on "always trust" but it didn't work. However, choosing "System" or "login" instead of "iCloud" worked for me. Thank you @Matt_SoundFingers & @dceddia. Is there any information why this does not work with iCloud Keychain? Any news about the bug report you've filed @DTS Engineer?