In 1020 uitype's fields, if the time elapsed in seconds is greater than 1 month, the conversion in human readable fails: it overvrite the number of minutes to the number of month.
SOLUTION:
in include/utils/crmv_utils.php in function time_duration around line 3062 find
$segments[strtolower($period)] = $count;
change it with
$segments[$period] = $count;
For the VTE developer:
you have defined an alternative $period array with only one letter to identify the period but if you use strtolower to populate the result array, the value 'M' became equal to 'm' overwriting the value in array.
Is it possible that no one of VTE customare that use SLA don't report to you this bug?