For this and a few other problems I ran into with Signal early in its lifespan -- problems that burned not just me but people I persuaded to adopt it -- I'll never put my neck out for this software again.
Reliability and a lack of surprises are the absolute most important features for the 21st century extension of the good ol' Plain Old Telephone Service, and it's sad and frustrating that anyone delivered chat software without getting that first.
Never mind that transitioning between iPhones (we almost bought her a new phone this year) has the same problem. That this is not supported invalidates Signal as a replacement for SMS or Whatsapp for many many non-technical users.