Cannot add to Gmail my iPhone/iPad contacts

Update 3
Prendo atto con disappunto che gli sviluppatori di Gmail non tengono in considerazione la necessità di risolvere i bug evidenziati dagli utenti e ciò anche a distanza di molti aggiornamenti da quando i malfunzionamenti sono stati segnalati. Adesso entrambi i miei dispositivi montano iOS 11 e:
1. il font è minuscolo e pressoché illeggibile;
2. il badge di notifica permane anche dopo la lettura delle mail;
3. da quasi 24 ore non funzionano nemmeno le notifiche push per cui occorre entrare costantemente dentro lapp e fare un refresh per scoprire che esistono molte mail non opportunamente segnalate;
4. persiste il problema originariamente lamentato che concerne limpossibilità di aggiungere alle mail destinatari presenti nellelenco dei contatti del telefono.
Abbasso la valutazione ad una stella perché peggio di così è difficile fare.
Sto per abbandonare Gmail in favore delleccellente Outlook (sperando che sia efficiente sul dominio google così come lo è su quello outlook/hotmail).

Update 2
Now Im on iOS 10.3.3 both on iPhone 6s Plus and iPad Pro 1st generation. Ive updated from iOS 10.2 just to see if this issue was depending by an outdated software. Unfortunately Im forced to rate only two stars as problems still there but the overall impression of Gmail app is really good. Its much more fast and responsive than it was already. Hoping that these few lines will be seriously held in consideration (obviously I uninstalled and reinstalled Gmail app after having updated iOS on my Apple devices but with no luck).

Update 1
I apologize but I must confirm my previous rating. Gmail team has not fixed this issue yet and I keep on being in serious troubles. Would you please sort this problem out?

Its since Gmail has changed interface that I cannot add my contacts stored in the iPhone/iPad address book as email recipients. And if I type the name of a contact in the "recipient" field I get the error message "Invalid recipient. Please enter a valid email address". I do not want to share my personal contacts with google so now its been several months that if I want to send an email Im forced to manually write the entire recipients address. And, obviously, its even worse if recipients are multiple. I tried uninstalling and reinstalling Gmail app but with no success. Problem occurs both on iPhone 6s Plus iOS 10.2 and iPad Pro 1st generation iOS 10.2.

*.onmyway.* about Gmail - Email by Google, v5.0.170910