This is most common with older CMS and some combinations with browsers (such as Internet Explorer) where the “allowfullscreen” attribute is filtered by the editor or the CMS.
This is an error in the CMS system that we cannot fix, but we have a workaround that MAY work in some instances. If this solution doesn’t work an update or bugfix of your CMS is the only remaining solution.
The workaround is to:
Login to Streamio and go the menu “Account settings” where you choose “General”. By checking the box “Use modified fullscreen attribute in embed/iframe code to work around older CMSs that erroneously filters out the “allowfullscreen” attribute.
Remember to click on “Update account” to save the new setting.