I have been constantly having this problem, as well as a few others, and we think it has to do with Mesh Streaming. You can disable it in a config file if you like but you’ll take a performance hit 
From what I’ve read it seems to be affecting a lot of folks with Ryzen 5xxx series processors for some reason? you can read more about it on this thread here: No reticle when ADS lasrifles - #18 by Kettun