Regression seems to have occurred in between MAME 0.193 and MAME 0.196.
Debugger traces suggest this might have occurred with changes to the KR2376 keyboard encoder device (a91c079afb1db0e9644436624702cee84e97fa7f).
Indeed it was related to that commit. The keyboard inputs hadn't been actually hooked up to the device for z80netf.
In fact even in the version with the basic loaded the keyboard does not work completely: for example the Backclear button does not work.
If I use version 0193 does the machine work?
How can I attach the keyboard inputs to the Z80NETF device?