eLearning course that fails to complete - any way round this?

We have a particular issue with 1 eLearning course that an external provider has created for us.  It's a simple eLearning course with some videos to watch and some text and graphics on a series of slides. The slides are supposed to complete when the learner scrolls to the bottom of the screen and clicks Next, however when the user gets the the last slide, only the final slide shows as complete.  The course will only show as In Progress in a learner's training record.  The only way round this that I've found is to zoom in and out of each slide - it's like all the content isn't fitting properly onto the screen. This has been tried in Chrome, Edge and Safari browsers on multiple devices, but all with the same outcome. Is there a particular setting in Docebo that would fix this at all?  Or is there something I can suggest to the content creator to amend? Thanks