In case anyone is interested ...
My colleague uninstalled Signal and re-installed it, and the procedure was pretty much flawless. So that's nice, except that we really don't know what went wrong first time, so have no idea whether it will also happen for other people.
Now I need to persuade more people to join Signal, and I'm reminded of this:
I found it difficult, So many wont let go of whatsapp because of the groups they are in.
Good luck !
@stannard In this case someone wanted a chat group and suggested WhatsApp. I said that I won't use WhatsApp, set up a group on Signal, then told everyone my reasons. I also expressed sympathy with the pain I was causing, but I think most (so far) have accepted that I had legitimate reasons and so bit the bullet and installed Signal.
One step at a time.
It was helped by the fact that my 90-year-old mother uses Signal, so for me to start using it was the obvious choice.
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