This observed in v2019, both build 20050 and ...51. Can't always reproduce this easily - under certain viewing angles of an assembly, sections of an object (with an opacity setting of less than 100%) will disappear. The included screenshot shows one case of this - the longer rectangular cover shell (with the two BNC connectors) has an opacity set to 80%. Between the XY plane and XZ plane this shell disappears exposing the circuit board inside. Anyone seen something similar - some setting I'm missing ? Thanks.