I had tested openEMR on what is now version 5.0.2 when I made the changes to the horizontal menu and created the option for a vertical menu for tablets and Smartphones.
Those changes worked well in iOS 10 and above and Android 8.0 and above Fire OS 220.127.116.11. At that time I could not get it to work on iOS 9 and below.
I was not sure how users were using older versions of openEMR in earlier versions of tablets.
May I suggest trying openEMR version 5.0.2 on newer versions of iOS and Android.
You could check this feature out by
This is done in Administration > Globals > Appearance > Responsive Vertical Menu Style for Tabs
Can be individualized per user User name > Settings > Appearance > Responsive Vertical
Menu Style for Tabs
If you are intersted you could check out these two PRs that dealt with this issue
Responsive Vertical Menu For Tab Based Layout Take 1 #2427
Responsive Vertical Menu For Tab Based Layout Take 2 #2431