I just (12/31/2020) downloaded and installed BETA1. After updating the taskbar disappeared. At least I think its the taskbar; the bottom bar and top bar. I found suggestions at another link that I don’t seem to have permissions to include. 
The updated set of commands that worked for me:
killall plasmashellrm ~/.config/plasma-org.kde.plasma/phoneshell-appletsrcplasmashell &
The bars appear after reboots. I can’t say after future updates.