Maybe I'm missing something, but if I have a symbol sitting on an artboard, the Properties Panel will have the "Replace Symbol" drop-down widget so that I can easily change it.

However - if that same symbol is grouped, or displayed under a clipping mask - direct-selecting it (Control + Click) - this option will be missing from the Properties panel.

CC 2017 did not behave this way - and the toolbar at the top of the window would always show this option when a symbol was selected. For users who utilize a lot of symbols within working files, or has to group things, makes replacing a symbol way more difficult than it was in CC 2017, and seems to be an enormous step backwards in terms of usability.

Can this be fixed so that it shows up consistently?

Illustrator Version: CC 2018 22.0.1 - 64-bit