To be more specific, it’s not that they dont show up. They are one pixel below the terrain. You can prove it by going somewhere deep like the docks in the pirate map. Basically any 2D texture is hidden under terrain (i.e. blazes oil or any spray) and this happens only on M1, since non M1 macs (even running on big sur) dont have this problem.
I got my Mac mini M1 today and was excited for the performance upgrade of the CPU vs my 2013 Mac Pro. I’m having the same issue with none of the targeting UI being visible. This is a major problem if you play cast on release (I think most people do) and it makes skill shot heavy heroes unplayable. Definitely needs to be escalated in priority with all the M1 silicon that is hitting the market.