I've had this same issue. I've tried building a few of my apps with manual signing and with automatic signing. They build and run in iOS simulators, physical iOS devices, and "My Mac (Rosetta)", but not for "My Mac (Designed for iPad)".
Edit:
Since I believe this is the exact same issue, I'll post some more of my error details in case this looks familiar to anyone. If it turns out to be a different issue, I'll start a separate thread.
This app could not be installed at this time.
Could not install at this time.
Failed to verify code signature of /var/db/appinstalld/Library/Caches/com.apple.mobile.installd.staging/temp.NrLsa7/extracted/appname.app : 0xe8008015 (A valid provisioning profile for this executable was not found.)
Additional Details:
This app could not be installed at this time.
Domain: IDEInstallLocalMacService
Code: 1
Failure Reason: Could not install at this time.
Recovery Suggestion: Failed to verify code signature of /var/db/appinstalld/Library/Caches/com.apple.mobile.installd.staging/temp.NrLsa7/extracted/appname.app : 0xe8008015 (A valid provisioning profile for this executable was not found.)
System Information
macOS Version 11.0 (Build 20A5299w)
Xcode 12.1 (17222)