Thanks Mehatz.
What is the process to update? My settings (emails and licence key) in the Update section of the template control panel were already filled in but I cannot see a button to update?
EDIT: Just tried to update the template by the normal route (download the template from your site, update via the Extensions section) and it's showing as version 4.0.2 which I believe is the latest version, yet the Joomla 5 pre-update check is still listing Helix 3 as having issues which may cause the update to fail.