Well, turns out mame wasn't happy with the input --> port --> tag parameter in my CFG's that 0144 was creating and was stripping out all game input data in 0148.
To fix this, you have to add a colon character in the tag field, see the example below:
You will see a line like this:
<port tag="IN0" type="P1_BUTTON1" mask="16" defvalue="0">
Change it to this:
<port tag=":IN0" type="P1_BUTTON1" mask="16" defvalue="0">
All these tags will be different in your files, you just have to add the : where necessary.
Notice the colon character in the tag parameter. I have no clue why this is required now. Can anyone shed any light on this?