I am since today in Lastpass 3.3.2 and I really would like to keep all the standard settings in Lastpass.
My Aquamail works actually fine for me. The only change I did in Lastpass was to:
Go to the LastPass App > Preferences/APP FILL tap > Edit App Association > select "Aquamail" and "AquaMail Pro Activation" > choose 'Do not show fill window'.
Reboot your smartphone. If it is still not working properly, reboot and go first in Lastpass as I mentioned above on October 09, 2014, 09:08:30 am.
This workaroud was also mentioned/updated from Kostya in my answer on October 08, at 10:28:29 pm, but I did not see it until today.