After some recent updates in Manjaro all is working again

Thanks for the reply, much appreciated

My usual/default user account, in which the GUI doesn't load belongs to the following groups

sys disk lp wheel uucp lock network video audio optical storage scanner input power users vboxusers naesk

whereas the secondary user account where the GUI does load belongs to these fewer groups

disk lp uucp network video audio optical storage scanner power users vboxusers seank

Until I can find some resolution, I'm now using my secondary account purely for music production.

It seems I can sucessfully launch the GUI by logging out of my existing user account, and login as a different account and launch PD from there.

Having installed pd via pacman on Manjaro Linux

Kernel: 4.14.10-2-MANJARO x86_64 bits: 64
Desktop: Xfce 4.12.4

$ whereis pd
pd: /usr/bin/pd /usr/lib/pd /usr/include/pd /usr/share/man/man1/pd.1.gz

No matter whether I launch it from the Applications menu or CLI it doesn’t seem to launch the GUI interface

$ pd -gui
input channels = 2, output channels = 2
Pd-0.48.0 ("") compiled 15:51:15 Dec  8 2017
port 5403
TCL_LIBRARY="/usr/lib/pd/lib/tcl/library" TK_LIBRARY="/usr/lib/pd/lib/tk/library"   wish "/usr/lib/pd/tcl//pd-gui.tcl" 5403
Waiting for connection request... 
... connected
/usr/lib/pd/bin/pd-watchdog