Problem persists still in Chrome and Safari using Monterery 12.1 (21C52) on MacBook Pro M1 (2020 version). Scroll bars disappear, initially with otherwise intact scrolling functionality (- ie using two fingers on track-pad), then window freezes completely un-scrollable a few minutes later, albeit cursor retaining other track-pad driven functionality (clicking etc). At this point, scrolling function (two fingers on track-pad) is restored by a restart, and scroll bars then reappear temporarily, only to disappear when fingers removed from track-pad. Placing of cursor over position of invisible scrollbar 'thumb' does not restore their visible presence, but application of two fingers to track-pad does do so. Positioning of cursor over 'thumb' will move then move both scrollbar thumb and scroll page (in old fashioned way). Further freezes occur periodically, when scrolling function becomes entirely refractory to two fingers on track pad again and further reboot necessary. So this problem's at least four months old. Why is it being neglected?