Number settings do not get saved

[LLD]

I need to save 2 types of unique account numbers for my employees, i.e. 

Provident Fund account number which is 12 digits long, and

Insurance number which is 10 digits long

For both, I choose -

• column data type as Number,
• Numeric digits as 12 (or 10),
• display mode as Auto
• deselect 1000s separator,
• set maximum value & minimum value as 999999999999 and 100000000000 respectively (for insurance this is 9999999999 and 1000000000 respectively),

but as soon as I save, and the page refreshes, all settings are missing and it looks like this...

pls help. I don't know what I'm doing wrong