Appears release 3.21123.25 introduced a bug in the software.
I have an App that is working, without error, as published under 3.21115.37. If I open this App, in edit mode, to make changes, now under release 3.21124.16 I get the error. This is on opening with no changes made.

I have other Apps that I have been building that I cannot release due to this new error.
I have seen suggestions that I could use Monitor to investigate. To do this I would need to publish and introduce an error to a live environment. Not a good option. Also the monitor does not highlight easily where the issue is.
Can you please fix this release or roll back to one that doesn't have the issue, or at least tell us what is causing the problem?
Thanks