A new version of the Visible app appeared this morning. Installed. Version 4.2.0.
Deleted previous esim from Settings:Cellular:Visible
In app step through Switch Now
enter IMEI for your phone (on iPhone the IMEI can be found in Settings:General:About)
Continue with esim install
First up couldn't make a call.
calling in first said "user has not set up voice mail"
After a few mins it was working.
All done while waiting 40 mins in chat queue.
@capbrown50 @AY I can only guess because I don't have a physical SIM on this phone. Perhaps something along the lines of reinstalling the SIM and running through the activation process again from scratch? But because of the physical sim you may be tied in to having to rely on Visible Customer Support.