I uploaded the new .sppkg package to the SharePoint admin centre > Manage apps (replacing 4.2.0.0 with 4.2.3.0). Made sure that "enable this app for all sites" and "Add to Teams" were selected. The upload seemed to go OK and the app is enabled.
When I try to add a new tab in Teams, however, the org chart app doesn't show up:
I went back to the Manage Apps page, selected the app and tried clicking "Add to teams", but get an error:
"Couldn't add app to Teams"
"Check your network connection and try again"
I've checked the recycle bin (first and second stage) to make sure there are no older versions hiding there. Any ideas on how to fix this?