Well I seem to be following your directions, but it frequently fails for me. I’ve never been able to tell what I’m doing wrong or different between times it works and times it fails. Failures occur across different aircraft, across different airports/approaches. ILS might be more reliable, but sometimes fails. RNAV seems less reliable, but sometimes works.
I use NAV mode to follow the flight plan, then switch to APPR a few miles before the FAF. If it doesn’t capture glide scope, I try hitting APPR off and on a few times as soon as I can to try to get it to pitch down, but it never works once it has failed the first time.
Manually descending and recapturing has never worked for me. Only manually doing the landing works.