I didn't want to sudo it juuuuuuust in case.   :D

sudo rm -r /var/cache/app-info

----------------
 
ronnie@ronnie-desktop:~$ sudo appstreamcli refresh --force --verbose

** (appstreamcli:5519): DEBUG: Refreshing AppStream cache
** (appstreamcli:5519): DEBUG: Reading: /usr/share/app-info/xmls/org.freedesktop.fwupd.xml
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial_universe_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial-updates_main_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial-updates_restricted_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial-updates_universe_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial-updates_multiverse_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/security.ubuntu.com_ubuntu_dists_xenial-security_restricted_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/security.ubuntu.com_ubuntu_dists_xenial-security_multiverse_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/security.ubuntu.com_ubuntu_dists_xenial-security_main_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/security.ubuntu.com_ubuntu_dists_xenial-security_universe_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial_main_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial_restricted_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: Reading: /var/lib/app-info/yaml/gb.archive.ubuntu.com_ubuntu_dists_xenial_multiverse_dep11_Components-amd64.yml.gz
** (appstreamcli:5519): DEBUG: No metadata-specific subdirectories found in '/var/cache/app-info'
** (appstreamcli:5519): DEBUG: Detected colliding ids: plan.desktop was already added with the same priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: flcheckers.desktop was already added with the same priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: flblocks.desktop was already added with the same priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: flsudoku.desktop was already added with the same priority.
** (appstreamcli:5519): DEBUG: Replaced 'firefox.desktop' with data of higher priority.
** (appstreamcli:5519): DEBUG: Replaced 'thunderbird.desktop' with data of higher priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: thunderbird.desktop was already added with a higher priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: org.gnome.Software.desktop was already added with a higher priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: firefox.desktop was already added with a higher priority.
** (appstreamcli:5519): DEBUG: Detected colliding ids: language-selector.desktop was already added with a higher priority.
** (appstreamcli:5519): DEBUG: zathura-pdf-poppler.desktop extends zathura.desktop, but zathura.desktop was not found.
** (appstreamcli:5519): DEBUG: WARNING: Skipped component 'com.steelseries.rival-legacy.firmware': The component is invalid.
** (appstreamcli:5519): DEBUG: Removing old rebuild-dir from previous database rebuild.
AppStream cache update completed, but some metadata was ignored due to errors.