Hi Loren,
I have had a similar problem which was the guide line grips would not appear, they are a bit hard to move and place without their grips. It was reported back in August, My case report went back to Graphisoft along with files etc, and as i was told it was supposed to be fixed in the next update. There has been an update with fixes but not for this problem. There is still a problem with the Trace Reference and the Renovation filter in AC21 that slows the performance of my PC, and has been very annoying to me.
Still waiting for the next update I suppose...
AC19, 20 & 21 Win10 64 bit
Intel Core i7 - 6850K
2 x Nvidia GTX Titan Black - SLI
2 x 16 GB DDR4
2 x 24" Asus Monitors