Nixie tube has strange blue lights
Firstly, max ignition voltage for the IN-12 is 170V so you are cutting it a little close with the 175V supply, but depending on the converter i'd say that probably won't be an issue.

What i do suspect from your images, though, is that you have switched (or somehow shorted?) your connections between the grid and the 1-cathode, leading to the 1-cathode acting as your anode instead of your grid.

If i am reading your images correctly, you can see the grid lead glow orange when you try to display the one, and the blue glow (typically associated with the anode) appears to be emanating from your 1-cathode.