Attempted to create a cart using the following:

Hardened Drill
Standard Hull
Coal Engine
Large Railer
Bridge Builder
Height Controller
Liquid Sensors
Side Chest
Top Chest
Internal Storage x2

Assembler used up energy (including about 2.5 stacks of charcoal), then the assembly bar reached 100% and the 'Assemble' button highlighted again...But no card was available in the output. Basically it just vanished a ton of very expensive components and cost me 2.5 stacks of charcoal to do it. :6

Tried in solo creative mode. This produced a cart but the cart was bugged.

In creative mode, put down an assembler with a creative module on it. Built a cart using standard hull, hardened drill, coal engine, large railer, bridge builder, height controller, liquid sensors, side chest, top chest, internal storage (x2).

The assembler produced the cart but I was unable to place it on track. When I tried I saw the message:
"The cart failed to be placed into the world, this is due to an issue with one or more modules. Please post your log on the issue tracker here: https://github.com/modmuss50/SC2/issues"

latest.txt

...I was about to break my assembler and realized that it was at 99.999% complete.

Seriously.

So I fed it a piece of charcoal and it gave me my cart and I'm an idiot thank you very much.

Closing ticket.

Edit: checked the github for SC2 and this does not appear as an issue there (their issues all have to do with carts which are already created).