What a f*cking waste of 3 days RE effort. I thought Ghidra was going well until tonight.
Then I started losing random sections of work; code and data sections would arbitrarily revert to 'unknown', losing all comments and memory references with them.
At first I thought it was my fault, but after going through and 'fixing' all the code/data sections again (and retyping a bunch of comments), I saved and quit and then re-loaded only to find that other random sections were gone. After a few passes of this fruitless exercise I gave up.
It is completely and utterly unusable.
This is in addition to the minor inconvenience - in comparison - that the Z80 core doesn't know about the undocumented instructions. And my project uses them. A lot.
Ghidra, you suck. Welcome back IDA Pro!