In case anyone else experiences this issue, it was the DPI settings.
Received a new widescreen laptop at work, which defaults to 125% DPI. I assume that is why when chrome zoom was set to 80% it worked fine (video attached in first post)
I changed the DPI back to 100%, set the chrome browser at 100%, and everything works as it should.
There are a number of posts relating to DPI settings in this forum, however I didn’t know what I was actually looking for to fix this issue.
Now I have to back through the module and realign all the text since starting this module 😐
At least it is sorted now.