As discussed here: Reddit - The heart of the internet
I upgraded from the latest gramps version to 6.0.0 today. I think this caused a config reset on my system. The problem was, that the default gramps storage path changed as well (I think).
Old default path on macOS: ~/.local/share/gramps
New default path on macOS: ~/Library/Application Support/gramps
It may be possible that I set the old path myself, but I am pretty sure I didn’t. So there are two potential issues (the config reset and the default path).