Internal Slices have the from_date_offset Attribute, which is a negative number of periods for that internal slice to go back (past) from the "From Date". For example, M_ALC internal slice has 36 periods, that should cover 12 months in the past ('-12' from_date_offset), and 24 months from (and including) the current month.
Periods for a TSV do not follow this rule, all periods are covered starting the From Date and to the future, no periods are available in the past.

Steps to Reproduce:

1. Check the periods for the M_ALC (Allocation, Monthly) timeslice, in the PRJ_BLB_TIMEPERIODS DB table.
   from_date: Feb 1st 2019, num_periods: 36, from_date_offset: -12
2. Go to Home > Projects > [project] > Team > Details
3. Configure TSV to display Monthly Allocation, for 1 period only, starting on Feb 1st 2019.
4. Values will be displayed if there is any, and no error will be shown.
5. Move the TSV to display January 2019.

Expected Results: No error is displayed, as the TSV should display Feb 2019 - 12 months (as early as Feb 2018), to Feb 2019 + 24 months (to Jan 2021).
Actual Results: "Alert: The time periods requested do not exist. Review the column's Time Scale settings." is displayed. Available periods for the TSV go from Feb 2019 to Jan 2022.

Workaround: Ignore from_date_offset value and configure the From Date with the date the first period should be available.

This is working as designed. The from_date_offset is only taken into account when calculating the From Date (e.g.: in a new Clarity PPM deployment or when doing a full re-slicing). Once the From Date is set, the periods available start in the From Date, and finish on the sum of the From Date and the Number of Periods.