Construct 3 and Construct Animate web exports can work offline. So long as the project has been downloaded once while online, the user can successfully load the...
Hi AnD4D - we had this issue when building our game. We found it happens if there was any other instance of the game in an un-updated state running on a different tab. Which happens a lot with building and testing. We added text to users saying 'close all other instances of the game' then hit the button to reload. That solved it for us. Hope that's helpful.