I would suggest that the tool tip for the "reset game and collect doubloons" button be below the cursor, rather than above the cursor, as it covers up the doubloon count.
I think when you buy the autoseller, the amount getting deducted is from the next one up and putting your total money into a negative position, but displaying as 0. I think that's the issue, but I could be wrong.
Thank you for playing! The 'probe' command tells you if the port is too low / high.