I think I've got the same problem trying to download the new Star Wars. I've got 19.8GB system memory and 101GB microSD memory available.
On the switch, I've tried archiving all of the games and re-downloading on to the SD card where possible, I've tried hard restarting the console, and I've deleted a few games we don't use.
On Minecraft, I've deleted most of our games, and have tried downloading other packs (they've worked). If I try to download the Star Wars pack again after it fails, I can see the space required increase by about 170MB every time (same problem that John McGrath noticed).
One other data point that I can't track down with Nintendo anywhere online, is that if I try to check for corrupted data using the switch system settings (Data Management -> Manage Software -> [[GAME]] -> Check for Corrupt Data), it doesn't have any problem doing so for any other game, but when I try to do it for Minecraft I get a system error 2001-0106.
Is anyone from support monitoring this thread?