Calculation Rules Not Being Applied Weirdly

PeopleSoft HCM 9.1 (plan to upgrade to 9.2 this year)

We have several age-based benefits (e.g., Supplemental Life) that are normally set to "Last Year On" (date of open enrollment) on the first but are briefly reset to "This Year On" (date of open enrollment) on the date of open enrollment. I'm not sure why the business users do this. E.g.

LFEE 2018-01-01 L

LFEE 2018-10-01 T

LFEE 2019-01-01 L

This year they forgot to toggle back from T to L on the change of the calendar year, so employees began to be overcharged benefits deductions for those benefits. They then added (and backdated the effective date of) the calculation rules, BUT the employees are still being overcharged.