After I enable my YubiKey, how do I access my LastPass mobile apps?
In your YubiKey settings:
LastPass Icon > My LastPass Vault > Account Settings > Multifactor Options > YubiKey
make sure that the "Permit Mobile Device Access" setting is marked as "Allowed". This means you can login to your smartphone or tablet mobile app without conflict.
You will however, need to "enable" the device in your settings as well to allow this device to login to your account. Please see the helpdesk here for information on that - https://helpdesk.lastpass.com/account-settings/#h5