I’ve noticed a few problems with R1’s printing - namely that it doesn’t present the printer information to some programs, or those programs don’t know how to access the printing module…
Becasso - prints
Beam - sees the printer but doesn’t print
LibreOffice - no
KWrite - no
Mail - no
Pe - prints
Scribus - no
Maybe these programs need a tweak to point them in the right direction to detect the printer?