Access code pages show blank when published (all browsers)

Hi team, any help appreciated. I am trying to use the access code feature to make a self guided escape room resource. However, any pages on which I embed the feature into show as blank when published and played (in all browsers), ie there is no button/box etc to enter the code(s). This is the same whichever of the different options for display I use and with all different password types. Can anyone advise on this issue?  Thank you.