Hi J_231,
I apologize for all the trouble it has caused and sorry about your time.
As per your description, I have meet same behavior as you mentioned (it always returns 1), see image below for you reference:
To get month as a number (1-12) from a date the Syntax is “=MONTH (date)”. The MONTH function extracts the month from a given date as number between 1 to 12. Here is example screenshot.
For reference: MONTH function
Since, as per your description it seems you want to convert serial number(1-12) to Month name or****to return a month's full name, you use the TEXT function as shown in the following formula example: =TEXT(A9*29,"mmmm")
I appreciate your patience and understanding.
Best Regards
Waqas Muhammad