Power Automate SharePoint Update Item Succeeding but Not Updating Value for Lookup Multi Select

[TrentonPaul20]

Hello,

I have two SharePoint lists - Submissions and Responses. I built a flow to

1. collect response data (data coming from Outlook Adaptive card),
2. create a record in the Responses table, and
3. update the corresponding submission in the Submissions table by adding the Responses record to a multi-select lookup column called Reviews.

To accomplish this, I originally used the Update Item connector and tried updating the Reviews column with an array of IDs. This array is a combination of the existing items with the ID of the new record just created in Responses. The array was formatted as follows:

{
  "Id": 1,
  "Id": 2,
  ...
}

Derived from this solution: https://powerusers.microsoft.com/t5/Building-Flows/Updating-SharePoint-Lookup-Column-with-multiple/m... 

Although the Update Item action succeeds, the Reviews column doesn't update with the new data. With no luck, I tried using the SharePoint Send HTTP Request action instead. I got this one to successfully update the Reviews column with records I manually created in the Responses table. However, it still won't link records that were created with the Create Item action that I'm using. The body for the HTTP POST request is in the following structure:

{
  "ReviewsId": [1, 2, ...]
}

 Reviews is the internal name of the column.

Any ideas as to why this Reviews column refuses to update? I've verified using additional queries that the data isn't updating to rule out any browser cache issues when looking at the list.

Thank you.

[SudeepGhatakNZ]

@TrentonPaul20 

Since you said that you are not getting an error message, could you check the version history and see if the item gets overwritten after a successful update?

[TrentonPaul20]

@SudeepGhatakNZ 

Great idea, but I checked and it seems to log every attempt to update the value, but you can see that it records no changes (the blank records):

[TrentonPaul20 · Accepted solution]

Found the answer to my specific issue. Ultimately, the issue was that I wasn't assigning the Title column on my Responses table. For some reason, that prevented the lookup column from updating properly. Once I set the Title, it worked as intended. Thank you for your help.