Nope, that has been tried, it hits the same bug.
Not that there was any mentioning about this in the release notes, but still not working with 18.104.22.168 when using dialler and **21*number#.
However I actually learned something new recently that changed my need for this. Instead of doing the traditional call forwarding manually every time, when using “if out of reach” call forwarding, I can keep it on constantly knowing that when I enter places where there is no signal it will automatically forward my calls.
Still not working on 22.214.171.124, either. Not just call forwarding but also call barring and call waiting. Call forwarding settings also behave strangely.