Xcode – Installation error on iPadOS 17 and iOS 17: "Failed to verify code signature"

I have all my Apple devices up-to-date (macOS Sonoma 14.0, iPadOS 17.0.2, iOS 17.0.2, watchOS 10.0.1, Xcode 15.0). I have an app I am working on, Date-O-Rama, and until a few days ago, Xcode installed it on my iPad and iPhone. Now I am getting cryptic errors when I try to install and run a new build of Date-O-Rama on either device:

Error message for the iPad:

לא ניתן להתקין את ״Date-O-Rama״
[Translation from the Hebrew:
Could not install “Date-O-Rama”.] Failed to verify code signature
of
/var/installd/Library/Caches/com.apple.mobile.installd.staging/temp.cRw8yc/extracted/Payload/Date-O-Rama.app
: 0xe8008001 (An unknown error has occurred.) Verify that the
Developer App certificate for your account is trusted on your device.
Open Settings on the device and navigate to General -> VPN & Device
Management, then select your Developer App certificate to trust it.

Error message for the iPhone:

Failed to install the app on the device.

I have tried making sure the developer app certificate is installed on my iPhone and iPad. The devices claim the certificate is not trusted and do not let me make them trusted.

For comparison: I can install and run Date-O-Rama without problems on my MacBook Pro (in Catalyst).

Does anyone have any idea how to fix this problem?

Thanks in advance for any help anyone can provide.