Having very odd display issues, (see attached files) basically I draw a curved shape in outline, this views correctly, then view it in overprint mode, this views correctly, view it in standard mode and it is awful, I've tried restart/making a new document etc etc, still views awful ????

please advise..... don't ask me to work in overprint preview as one of my others posts states, that is ridiculously slow.

Mac OS 0.15.6,
iMac (Retina 5K, 27-inch, 2019)
3.7 GHz 6-Core Intel Core i5
64 GB 2667 MHz DDR4
Radeon Pro 580X 8 GB