Currently going through a large Office 365 migration and so here are a few issues I encountered and their solution.
– Problem: The 365 Portal ( 365 App Launcher ) is missing Word, PowerPoint, Excel, etc icons, even though 'Office Online' licenses have been assigned.
– Cause: Admin Center, SharePoint, Settings, 'OneDrive for Business' was set to Hide. The option hides icons for all related services.
– Problem: For OneDrive, Word, etc, the 'Share' and 'Invite People' is missing the Share button, even though sharing is enabled in the SharePoint settings.
– Cause: FireFox / Chrome AdBlocker was blocking the button, disabled AdBlock for the domain and reloaded the page.