Thanks for the reply, I greatly appreciate it.
I was recently trying to
build:ios (not bundle as you noted) on my Ubuntu 18.04 machine and I wasn’t able to create an IPA that was acceptable to Transporter. (error ITMS 90956)
I managed to work around the issue by installing an compatible version of Xcode on a 2011 Macbook I had lying around, and doing the same
build:ios I was now able to send the IPA through Transporter.
As a note, I was not successful using the Macbook until I downloaded Xcode, this prompted my question here on the forums.
I massively appreciate any more input, thanks.