hp 9…, win 10;
i formatted to time but got ZEROS. ?
You format a cell using date or time format codes only when the cell contains a date or time value. A date or time value is a number that indicates how many days had passed since some point; that means that measuring time, you deal with fractions of days. You get date/time values when you enter dates or times to cells directly (given that you enter strings that are convertible to dates/times in your locale and settings); or from functions returning that (like DATE or NOW); or by performing arithmetic operations with those values (like adding time spans to dates).
When you use MINUTE function, you don’t get time in return. You only get a whole number like 28. When you try to interpret it as “time” (by applying time format codes to the cell with that number), Calc looks for fractional part of that whole number (in vain), and returns how many minutes are there in the absent fractional parts. You are using it wrong. Just format it as number.
And given the number of your questions about dates and times, you should had already became world-leading expert in using datetimes in spreadsheets. Sigh.