Many glitches in Animate that need fixing...

Hi, recently I began facing many issues with Adobe Animate (the newest version). To fix these, I’ve tried restarting Animate and my computer, reinstalling Animate, using an older version and resetting/deleting preferences and cache. The glitches I am currently facing are that there is a random black bar on the right hand side of my Preview panel that I cannot get rid of, even if I zoom, as well as sometimes when I break apart symbols or transform shapes, some parts either randomly change colour or get deleted. Also, when I use the Free Transform Tool, timeline playback gets extremely laggy and slow. So far, the only was to fix this is to use CS6 (at least for the black bar), though I need the camera tool and frame picker. I use Mac OS High Sierra (the newest version) and a 4k monitor that is scaled to 3008x1692 Are there any other ways to fix these issues?

Thanks