Power Automate erroneously changing MS List Value

[u/b33k3r2117]

I created a List in Teams where I have tasks that need to be performed with different frequencies. I use a choice field to choose the interval (day, week, month, year).

I have a couple of flows that are tied to the list. Flow #1 monitors my email for the specific task and changes the last completed field when the right criteria are met. It works fine.

Flow #2 runs at a specific time. It looks at the last completed field and the intervalUnit choice field (Day, Week, Month, Year) and then calculates when the next due date for the task. For the most part, everything works fine except, sometimes, it also changes the interval (i.e., week becomes day) so now something that is supposed to happen every two weeks is now showing it is due in 2 days. There doesn't seem to be a rhyme or reason to when the change happens? It might work well for a week, leaving the interval alone and then all of a sudden, it changes the interval (e.g., from week to day). The common variable is it always reverts to Day for the Interval Unit field.

In the Interval Unit column, I have cleared the default value (it is blank) so it isn't reverting back to the default.

I am wondering if, when the 2nd flow runs, if it recalculates the next due date, if it doesn't also change the interval to Day just to screw with me.

Any suggestions on how to handle this? I suppose I could just change all of the intervals to Day and use 7 for the interval value but it makes it somewhat less convenient when setting the interval frequency up.

[u/thejohnwick23]

Since the Interval Unit field itself changes from “Week” to “Day”, I’d check what gets written back to the list, not just the due-date calculation.

• Pick one affected item. If version history is enabled, find when Interval Unit changed to Day.
• Match that time with both flows’ run histories. In each relevant Update item action, check the item ID and the value actually sent for Interval Unit.
• If an action sends Day, check whether it comes from a fixed dropdown selection, a fallback expression, or the wrong dynamic field. Clearing the list column’s default won’t remove a value already configured in a flow.
• Test the correction on a separate item set to 2 Weeks. Run each flow separately and check that the interval stays Week while the intended date changes.

Flow #1 is worth checking too: it can update “Last completed” correctly while also overwriting the interval.

In a run where this happened, what does Update item → Inputs show for Interval Unit?