Using the remote build process (making an iOS build from Windows with a remote Mac) no longer functions properly on iOS 14.5 devices.
It's possible to create an ipa, but it's not actually possible to sideload it onto device due to new code signing standards required by Apple. See: [Link Removed]
When code signing occurs directly on a Mac, this is a non-issue, since the Mac will code sign correctly. However, with the remote build process, it appears that the resigning that occurs is no longer compatible with these new standards.
Relevant code includes PerformSigning() in CodeSigning.cs which references a cVersion2 from MachObjects.cs in the iPhonePackager. This cVersion2 is set to 0x20200, which does not align with the above requirements from Apple.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-114823 in the post.