Not an issue on our iPads - has always worked. Maybe because these iPads are too old?
iPad 3, iOS 10.3.3
I just confirmed that this continues to be an issue on iOS 11.2 in Safari, on the newest iPad Pro. However, with this version, sometimes the top menu buttons can be activated by long-pressing on them, but you have to place your finger squarely over the button, and tap directly down on it without accidentally moving your finger sideways while doing that, and you have to long-press for about one full second, after which the menu drops-down, but it simultaneously highlights the text of the button for copying, which is distracting.
I had a chance to play with a current iPad last night. It seems that this is only an issue with the top-menu buttons that have menus behind them. If it is a straight button, like Calendar, Flow Board, or Messages, the tap registers without any problem. Taps are much more difficulty for the buttons that open menus when hovered over or tapped-on on a tablet, like Patient/Client, Fees, Procedures, New Crop, Administration, Reports, Miscellaneous, and Popups.