Typically I update everything using the following composer command:
composer update "drupal/*" --with-all-dependencies
Usually the above command works without issues, but sometimes there are some weird conflicts. Look at the Drupal forums found this command that worked perfectly.
First get a list of requirements:
composer show --no-dev --direct --name-only | xargs
Use the following command and above output to generate a new set of requirements, with minimal specification of versions so composer can figure out whatever works.
composer require <output of above command> --update-with-all-dependencies
Drupal support post can be found here.