Select Same Fill Colour not working

This has been going on for a while. Randomly, there are days when the "select same ___" commands (keyboard and using the dropdown menu) don't work. I have an illustration with a bunch of items the same color and I try to select same fill color, nothing happens. I've tried restarting AI and it doesn't help. Current version of Mac OS and current version of AI, but it's been happening for months.  I tried other suggestions on the forum; looking for clipping masks etc. nothing is working. Can anyone help? Thanks.