Concat for multiple selections in a listbox

[kdurgp8]

Hey all, 
I see that many people have asked similar questions around getting the selection in a listbox. I have a list that is pulling from Sharepoint and displaying the "Title" field. I would like to concat all the selected items into a string so that I can later send them into an Automate Flow. I feel that I am close, but I am missing something. 

In this screenshot, I can see that I have 3 values when I hover over the "Title" in Line 1. 

But when I hover below on the variable name, it shows the value is "Blank".  

... And to prove that the data isn't storing and submitting, here is a screenshot in Power Automate showing the payload:

Any Ideas? Thanks in advance!

[kdurgp8 · Accepted solution]

Like many others, I was able to solve this. My solution was:

Set(selectedSites, Concat(ListBox_Sites.SelectedItemsText.Title, Concatenate(Text(Title),",")));

Resource:
https://powerusers.microsoft.com/t5/Building-Power-Apps/Concat-Multiselect-Listbox-expression-error/...