New Picade+RetroPie Control Mapping issues (fresh out of the box)

[brooksoid]

Hello all.

I'm having problems with double-mapped controls with a vanilla RetroPie install. I've rebuilt twice now to try and confirm it's not my fault.

Here's my config:
Pi Model: 3B+. Original PSU. RetroPie 4.4, from SD image on RetroPie Website.
USB Devices: None. Controller: Picade HAT (new Picade). Emulator: lr-mame2003. Romset: 0.78.

I burn the SD image, boot the Pi(cade), F4 to exit control mapping. I setup wifi, and CURL the Picade HAT script, and map my NAS network drive in /etc/fstab appropriately (my roms live on my NAS).

I reboot the Pi(Cade), and go through controller configuration - setting up/down/left/right with the joystick, abxylr with the 6 coloured buttons, start/select with the front two buttons, lt/rt with the side buttons. I use select again for the hotkey.

I launch defender, and immediately notice that one of the buttons is mapped to fire AND thrust. I launch Track&Field, and when trying to enter my initials at the start of the game, one of the buttons is moving the initial selector left THEN RIGHT.

I launch rtype, and I can't move left. I plug my USB keyboard in and check the arrow keys - and I can't move left either.

This is without me having mapped any buttons explicitly in the green-hued RetroArch menu, or the TAB menu in Mame. I've also cleared out any .cfg files in the Mame roms directory to make sure nothing's interfering.

Initially I thought I was mapping things in the wrong place (ie using retroarch mapping when I should have been using mame, or vice versa). But the rebuild confirms that this double mapping seems to be present out of the box...

I've read the RetroPie docs and I'm none the wiser. In fact I still don't know whether I should be remapping controls in retroarch or mame. I suspect the answer is 'either'. Nonetheless, in this scenario, I'm not creating any mappings outside of setting up the virtual RetroArch controller.

Can anyone throw any light on this?

Thanks,

Matt.