Hi Jonathan,
This is a well known issue, there is plenty of information about ios on the forum if you search for it https://community.adaptlearning.org/mod/forum/search.php?search=ios&id=2.
Generally this thread seems to be the endpoint for most people https://community.adaptlearning.org/mod/forum/discuss.php?d=926#p4714.
The summary info is that ios support for scrolling content inside iframes is terrible. The only acceptable solution is to launch a new window to remove Adapt content from the iframe. This can be achieved with a simple launch.html page which opens a new window using index_lms.html or by using an extension like https://github.com/cgkineo/adapt-launchNewWindow.
Kind Regards,
Ollie.