I don't think that's correct.
If you're a reserve, look at your "pay statement" in DBMS. (not your time card; not your paycheck)
Reserves get the int'l override even if they don't break guarantee.
This happens to me nearly every month.

On the pay statement, you get paid for the int'l trips you fly (including the override) and then if you don't have 70 hours they pay you for the number of hours you are short of 70 (without the override).

ie = I flew 59 reserve hours in April and some of it included intl override. I got paid for all that flying including appropriate overrides. Then I got 11 additional hours of pay to get to 70. Logically, the 11 "guarantee" hours did not include the override.