Thanks for sending me the information.
The other online compiler which @piero.alberto used was Monaca (a competitor). Digging into it, we found that Monaca was using cordova-ios 5.0.1. That version is obsolete: apps using it won’t be accepted into the App Store.
We tried VoltBuilder again, this time also using cordova-ios 5.1.1. The app compiled and ran properly, showing the problems are the result of changes in iOS and Apple’s requirements, not from VoltBuilder.
BTW, here are Monaca’s build options. They’re seriously behind in their updates.
For the iOS platform, VoltBuilder uses iOS 6.1.1, while Monaca can only do 5.1.1. (Same as PhoneGap)
For the Android platform, Voltbuilder uses 9.0.0 while Monaca is on 8.1.0 That is also very old: the last version before 12 was 11.7.
For Xcode, Voltbuilder using 12.0, while Monaca is on 11.3. That is also very old: the last version before 12 was 11.7.
Here is a screenshot of the Monica build options: