Sorry that I could not understand the requirement very clearly.
The goal with this expression is to find the date of the Monday of each week of a given month.
Are you trying the find the every particular Monday for each row of ReadingTime field?
I tried to read the expression code, I assume the first DateAdd expression could be wrong ?(not sure here since I could not related it with requirement confidently)
As in =DateAdd(DateInterval.WeekOfYear,...) , the DataInterval.WeekOfYear returns only the week number from 1-53, so I think it is not supposed to use in DateAdd.
Tell me what you think, I would try to help further :)
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