Concatenate unique id

[Roger_Dalomba]

so I had a working concatenate unique id.

today I go on and now get a error message.
Expressions in schema ‘MASTER LOG_Schema’ have a circular definition. Check app formulas and initial values for column ‘ID’

the formula is working, so I’m lost why all of the sudden i have this message.

CONCATENATE([STOCK #],[VIN #],LEFT([First Name], 2) & LEFT([Last Name], 2))