Hello.
I also have this problem with WR841ND v9 and 19.07.2 and .3.
Tried also clean install (clean firmware mtd1 partition, tftp 18.06, upgrade to 19.07).
EDIT: What I see the problem is mainly with the Tiny package for 4MB devices.
I just tried to install community build of 19.07.3 and it works OK.
So this is probably the way, as 4MB devices were deprecated...