Textjoin not working correctly

I think that TEXTJOIN is not working incorrectly or i just don’t understand it … Can anyone help clarify
I show what I get vs what I think I should get in the attached spreadsheet

sample 1.xlsx

Solved this. Did not understand that I needed to end the formula with Ctrl, Shift, Enter to turn the formula into a Dynamic Array Formula. Yhen it works just fine.

Corrected sheet attached

sample 1.xlsx