This is due to the removal of package manjaro-hotfixes which removed two udev rules.
I don’t know what is exactly required but if you are not using systemd logind then you do not get properly authenticated which may create other issues like the ones you mention.
Search results for 'manjaro-hotfixes' - Manjaro Linux Forum - this will likely produce some information you can use.
This topic Need to put in pasword to open drive now, why? (drive is in system) - #7 by fsw contains the rules that was removed.